Based on a previous study … that elicited … personal accounts of sexual motivations … Meston, a sexual psychophysiologist, and Buss, an evolutionary psychologist compiled a list of 237 distinct [sex] motivations … In researching the  book [Why Women Have Sex] they asked over one thousand women to give a description of actual sexual encounters associated with any of these 237 reasons, mostly via online survey. These reasons are discussed in relation to the underlying motivations they point to and the likely evolutionary benefits they gave our ancestral mothers.(more)
The book Why Women Have Sex has many fascinating tidbits, and provoked many thoughts in me. For example, I noticed that the vast majority of the female sex motives discussed in the book are selfish, i.e., primarily intended to benefit oneself, as opposed to one’s partner. For example, even pity sex seems mainly selfish:
Here is how one woman described sex as a way of boosting her self-confidence:
I had sex with a couple of guys because I felt sorry for them. These guys were virgins and I felt bad that they had never had sex before so I had sex with them. I felt like I was doing them a big favor that no one else had over done. I felt power over them, like they were weaklings under me and I was in control. It boosted my confidence to be the teacher in the situation and made me feel more desirable.
The main altruistic sex motive is a part of “love”:
Of the more than two hundred reasons given for having sex, love [#5, to express my love, #9, I was in love] and emotional closeness [#12] were ranked in the top twelve for women. …
According to the well-known … “triangular theory of love,” love consists of the distinct components of intimacy, passion, and commitment. Intimacy is the experienced of warmth toward another person that arises from feelings of closeness and connectedness. It involves the desire to give and receive emotional support and to share one’s innermost thoughts and experiences. … Here is how one woman in our study experienced this [intimacy] dimension of love:
I fell that sex can be one of many physical expressions of love, though sex is not always an expression of love. When I make love with my husband, it is an intimacy, trust, and exposure of myself that I share only with him … because I love him. Sex can be a way of fulfilling my husband’s needs (physical, emotional, psychological) that can’t be achieved any other way and [it] lets him know that I love him and vice versa. …
Passion … refers to intense romantic feelings and sexual desire for another person, … “a hot intense emotion” characterized by an intense longing for union with another. …
Commitment … requires decision-making. … The long-term decision involves a willingness to maintain the relationship through thick and thin. Many women talked about how commitment was an essential component of love for them. In fact, some said that they used having sex as a way to try to ensure commitment from a partner they felt loved them.
So, out of the of 237 female reasons for sex, love is in #5,9. “Please my partner” is #11 (its #10 for men). On love, only one of its three parts, intimacy, has an clearly altruistic component. Six desired effects of intimacy are mentioned: experiencing warmth, giving support, receiving support, sharing experiences, showing love, and being shown love. Of these, only one, giving support or meeting needs, seems clearly altruistic (though even this could be selfish). So one of the six desired effects of one of the three parts of love, mentioned twice in the top ten reasons for sex, seems altruistic. Direct clear altruism is #11. Not nothing, but not a lot either.
People often complain that economists assume selfishness too often, and point to intense close relationships as clear evidence of altruism. But if even in this case our motives seem overwhelmingly selfish, economists’s usual approximation looks pretty good.
FYI, here are the top 15 female sex reasons, from that original survey:
1. I was attracted to the person
2. I wanted to experience the physical pleasure
3. It feels good
4. I wanted to show my affection to the person
5. I wanted to express my love for the person
6. I was sexually aroused and wanted the release
7. I was ‘‘horny’’
8. It’s fun
9. I realized I was in love
10. I was ‘‘in the heat of the moment’’
11. I wanted to please my partner
12. I desired emotional closeness (i.e., intimacy)
13. I wanted the pure pleasure
14. I wanted to achieve an orgasm
15. It’s exciting, adventurous