Study findings revealed that the average intimacy score in men and women in overtime increased due to consultation, so that women indicated 78% and men indicated 80% difference in the intimacy score compared to the control group after participation in the relationship enrichment program. Besides this, Yoo et al., in their study, concluded that behavioral-communication couple therapy not only increases the feeling of security, support, and creating safe behaviors but also can increase intimacy and build a desirable relationship (
25). Khamse et al. have also reported the use of applied intimate relationship skills to be effective in improving marital happiness (
26). Masoumi et al. have also reached similar conclusions, indicating the effectiveness of relationship enrichment consultation in sexual intimacy and satisfaction (
27). The results of the present study also indicated that intimacy has increased in the intervention group couples compared to control group couples in both temporal stages after the intervention. The results of the present research and similar studies indicate that couples' participation in relationship enrichment programs and improving the relationship through learning effective communicational skills will create better interaction and higher intimacy between the couples, and if both parties of a couple participate in such programs, the created interaction will lead them to better identify their behavioral and communicational challenges and eventually, find it easier to take steps toward solving their problems. Regarding women's sexual function score and its dimension, the results of the present study revealed that mean sexual function was initially 19.06 ± 3.96, which reached its highest value of 22.89 ± 1.54 three months after the intervention. However, Khaleghinezhad et al. reported the average sexual function score of rural women to be 24 ± 5 (
28). Sepehrian and Hosseini (
29) and Bahrami et al. (
30) reported the mean sexual function of fertile women was 21.2 ± 5.6 and 27.4 ± 7.3, respectively. These differences indicate that sexual function is an extremely complicated phenomenon and can be affected by various factors such as living conditions, interpersonal relationships, cultural, economic, and social differences, different populations, and even the different types of questionnaires available in this field. Regarding the dimensions of sexual function, results revealed that the mean score of all dimensions of sexual function, except for vaginal lubrication and dyspareunia, increased significantly compared to before the intervention in the group under counseling. These results are consistent with previous studies (
31). Both these studies indicated that sexual consultation had a positive impact on all the dimensions except for dyspareunia. However, the results of the present study were inconsistent with the results of Muhammad-Aliie study conducted in postmenopausal women that indicated dyspareunia score increased significantly after intervention too (
32). However, they reported having taught how to use lubricant in their training course, and since one of the causes of dyspareunia in postmenopausal women is vaginal dryness, it might be the reason for this inconsistency. On the other hand, factors such as a variety of infections, vaginismus, and endometriosis may result in dyspareunia in fertile women, which are different from the reasons causing dyspareunia in menopausal women. On the other hand, factors such as a variety of infections, vaginismus, and endometriosis can cause dyspareunia in women of reproductive age that are different from the reasons causing dyspareunia in menopausal women. Additionally, hormonal fluctuations and anxiety can also affect vaginal lubrication (
22). Results of the present study revealed that men's sexual function score and its dimensions increased significantly in three time stages in the intervention group compared to the control group. The author found no other study investigating the impact of relationship enrichment training on men's sexual function in Iran; however, there are similar foreign studies focused on men's sexual satisfaction and performance. Nelson and Kenowitz concluded that relationship enrichment interventions and intimacy have a positive impact on sexual function in men with prostate cancer (
33). Walker et al. found that intimate relationship training after prostate cancer improves male sexual function, especially during orgasm. Although the effect size was reported to be small to medium, it was suggested that longer interventions might be more impactful (
34). Difficulties due to sexual function in men and their intimacy are of great importance that the vast majority of men who experience sexual dysfunction will suffer more if there is a lack of intimacy between them and their partner (
35). The aforementioned studies are somehow consistent with the results of the present study and confirm the influence of intimacy on improving men’s sexual function even in cases who suffer from an illness. However, side-finding of the study indicated that among the five demographic variables (marriage duration, husband and wife’s education, the number of children, ethnicity, and occupation) and intimacy, only intimacy affects men’s sexual function, while both intimacy and the number of children affect women’s sexual function. According to the results, having more children decreases women’s sexual function. This finding was consistent with Afshari's study (
36). Several pregnancies and their respective complications, women’s unattractiveness after giving birth from their partner’s point of view, taking care of the children and their respective responsibilities, and being tired from looking after the children might be the reason for this finding. But the important finding of the study revealed that the intimacy variable in both men and women had a positive and significant relationship with improvement in sexual function. Although some studies did not report a significant relationship between intimacy and pain in the sexual function of women, couples with higher intimacy levels reported better sexual function and satisfaction (
37). Rubin and Campbell also indicated that increased intimacy is associated with greater sexual satisfaction in non-clinical couples involved in a long-term relationship (
38), which is also consistent with the results of the present study. Intimacy is a relationship protector and predictive factor for those suffering from sexual dysfunction since it balances some aspects of sexual function and distress. On the other hand, lower intimacy is associated with higher distress in those suffering from sexual dysfunction (
39). The inability to establish intimacy and a healthy relationship brings about many social, emotional, and physical consequences for couples. Actually, the life of most couples has turned into a static and intimacy-free relationship due to their unawareness of communicational skills and unhealthy communication style (
40). Furthermore, women who lack sufficient marital intimacy will experience sexual incompatibility with their husbands and refrain from being in any position leading to sex (
41). The interaction between intimacy and sexual function can play a synergetic role in improving the sexual function of the couple, which has a significant part in the continuation of marital life. One of the strengths of this study is the presence of both couples in consultation sessions. One of the limitations of this study was self-report data that cultural issues such as shyness and shame might be influential in responding to sexual issues. Moreover, intimacy is a complicated and dynamic phenomenon and cannot be simply measured and reported using a questionnaire. Development and use of more diverse measures such as conducting deeper qualitative studies might help achieve a more comprehensive image of empathetic responses and disclose further information in this regard.