Perhaps consider having no visible gender queues. Maybe go so far as to also not show names. If the goal is truely for friends, does the gender and name matter?
It doesn't, but the problem is that people aren't usually very kind to other people on the internet. So I can see a good chunk of users rollin' the dice and seeing if they match with attractive people, and if they don't, they just move along. This would ruin the experience for the other two people that are left hanging and feeling like shit. I really want to prevent that from happening.