Social constructs of friendship in the context of sexuality

(Don't attack Steve, please. This was idle talk at lunch)

Steve brought up an interesting idea today: that homosexuals were less inclined to make and maintain long-term friendships than heterosexuals because of the differences in how men and women view the world. He posited that heterosexual couples find it harder to interact with one another because of these differences, and so having outside friends is necessary for each, in order to have someone (or ones) to interact with that has a similar mindset. Homosexual couples, on the other hand, are more likely to have a similar mindset, and therefore find outside interaction less necessary (additionally, he pointed out the difficulty in maintaining a friendship with someone who is either a potential mate or competition - or both), and this may be part of the difficulty in maintaining a queer community.

He points out, of course, that these differences are not necessarily due to genetic or inborn differences, but rather differences in how men and women are raised. As a counter-example, he offered my parents, who tend to have few outside friends.

I'm not sure how accurate this is. Certainly, it's fairly accurate for me and for him, but we're both introverted anyway; I have few friends that I maintain regular contact with, and only a couple are women. And I don't have, in general, any real desire to change this.

I want to discuss this, but I'm not sure where to begin. Thoughts, anyone?