That's obviously not a straight (unintended) comparison. Men are still men, women are still women, whether they call themselves gay or straight - and if they are willing and able to follow the rules, it shouldn't be a big deal.
At this point, I don't believe you're being honest in your thought process. You're setting a double-standard.
Why do you have a problem with men and women living and showering together? If they're willing and able to follow the rules, why is it a big deal?
I'm assuming that you have a problem with this because of the sexuality involved between men and women; if that's incorrect, then please explain why it's not okay.
If my assumption is correct, then the reason you don't think it's appropriate for men and women living and showering together, also applies to gay men living and showering together, and gay women living and showering together.
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Added: And of course, the obvious conclusion: It also applies to gay and straight men living and showering together, and the same for women.
So why is it not okay for heterosexuals to live and shower together, but it's okay for heterosexuals and homosexuals to live and shower together?