Sex is a very individual thing, and each person has completely unique thoughts, opinions, emotions and desires regarding sex. Some of this is cultural, but a lot of it can help us to understand the dosha of a person.
Vata is creative, sensual, responsive and wary. They naturally have a low interest in sex, which serves them well physically because it can be quite imbalancing for them. Sex is important to them only as an expression of love, for they love to express themselves.
Vata may take some time to commit in a relationship, but once they do they are very faithful lovers. For this reason they may be considered cold sexually, but when they meet the right person they will be a surprisingly satisfying lover.
Vata really appreciates romance, beauty and art, and their partners would be wise to indulge them here as it will help allay their anxiety and warm their desire. They may not know it but traditional values and routine are very valuable. It can be helpful to plan to have sex ahead of time and enjoy all the courtship and foreplay that precedes.
Vata is most likely to have problems concieving due to stress, dryness, low body weight and disturbed Apana Vata. Travelling and general instability won't help, so Vata's parter can really help by appealing to their romantic side, cooking regular meals (the best thing anyone can do for Vata) and encouraging them to slow down and rest. Worry is their greatest enemy, and their sex drive can be switched off all too easily.
Pitta is fiery, ambitious, attention seeking and passionate. Their competitive nature may impede on their sex life by preventing them from ever feeling satisfied. Pitta people love to think of themselves as fantastic lovers, but a lack of patience and reliability may be frustrating for their partner. They tend to prefer spontaneity and power.
Pitta types may suffer from impotence due to excess heat burning up the reproductive tissues or Pitta's natural flow of movement upwards, instead of downwards (like fire). Pitta may indulge in sex more often than Vata, but go more gently in summer.
In matters of sex Pitta should take care to channel their enormous energy through their heart, rather than their sex organs or brilliant intellect. This will lead to virility, compassion and nobility in sexual relationships.
Kapha is enduring, balanced, determined, nurturing and hard working. Kapha is naturally very sensual, and considered a very good prospect for marriage. Their partners need only watch out for feeling trapped by Kapha, as they become very attached and can be greedy.
Kapha is unlikely to suffer from reproductive issues and will usually bear many children very easily. Enlarged prostate, endometriosis or ovarian cysts may be caused by Kapha, but most commonly, Kapha need only lose a little weight if they have any trouble conceiving.
Kapha can really benefit from excercise, and sex is one kind of excercise Kapha can be more easily persuaded to partake in!
For the best possible sex life you would be wise to know your partners dosha, as this will help you to seduce and stimulate them, meet their needs and understand when things don't go exactly as you hoped.
Special thanks to Maya Tiwari for much of the information in this post.