It turns out that nice guys do get the girl (but not these nice guys), and nice girls too! Altruism has been linked to more sexual partners and better relationships. There is a growing body of research that connects people who are emphatic are good partners to have in life. Over at Scientific American they have an article on how researchers are contrasting the concept that people need to be jerks to attract a mate.
Remember it’s good to be nice regardless of how much sex one gets.
This theory suggests that altruism may serve, in part, to convey one’s value as a mating partner, including one’s concern for others and likelihood of cooperating with future mates. Research has shown that we prefer altruistic partners, all else being equal; especially for long-term mating (the evidence for altruism being preferred in short-term mates is mixed). Not surprisingly, then, the pull to demonstrate one’s altruism can be strong. Some research has shown that men will actively compete with one another (termed competitive altruism) by making charitable donations to women. Interestingly, these charitable donations increase when the target of one’s altruism is physically attractive.