Sex File: Why is my fiance more like a friend than a lover? 

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I love my partner, now fiance, of four years dearly, but even thinking about having the kind of sex we used to have together feels . . . wrong. We can go weeks, sometimes longer, without having it at all. Should the passion have disappeared already?

Sex ebbs and flows in any relationship, but sexual frequency is primarily correlated with the length of your relationship. A couple in their 60s who have been together for six months will generally be having more sex than a couple in their 30s who have been together for six years. Comparing the relationship you have now with the relationship you had four years ago is not helpful because in the early stages of a new relationship couples experience such strong and spontaneous sexual urges that no one needs to initiate.

As a relationship matures and couples have had quite a lot of sex with each other already, the motivation to keep having it is driven less by sexual desire and more by the need to connect, to strengthen intimacy and to make each other happy. And sex really does make people happy. Research published has found that having sex has a positive impact on mental wellbeing that lasts for up to two days.

Although we are bombarded with quantitative guidelines on healthy behaviours such as eating five pieces of fruit and veg a day, getting eight hours of sleep or not drinking more than 14 units of alcohol a week, the guidance on how much sex is enough doesn't get half as much press. Research has identified the optimal amount, though. In 2015 a study of 30,645 people demonstrated that there is indeed a significant association between sexual frequency and relationship satisfaction - but the benefits are capped at once a week. After that more is not always better. The bad news is that few couples actually achieve a frequency of once a week.

That you and your fiance can go for weeks on end without having sex does not necessarily mean that there is a problem in your relationship. However, it is worth thinking about why it might be happening. Any big life transitions can have an impact on sex, often in unexpected ways. Although getting engaged is exciting, don't underestimate the pressure it can put on your relationship. Commitment is an emotional seesaw because it simultaneously reduces feelings of insecurity and uncertainty, while increasing the level of scrutiny that you apply to all aspects of your relationship, especially sex. Prior to your engagement I doubt you paid much attention to sexual frequency, but a proposal of marriage forces you to think about the future and, inevitably, start questioning everything.

Marriage is a leap of faith and no one can predict the future, so the only thing you can do right now is be completely honest with yourself and with your partner. Talk to him about your concerns and if it turns out that both of you have noticed the decline, but neither of you is worried about your sexual compatibility, stop worrying and get on with it. If, however, your instincts continue to tell you that your sex life is not what it should be, trust your gut because marriage doesn't tend to solve sexual problems.

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