You don't need to be having vaginal sex to use a femidom, by many accounts they're better for anal sex. Men can also take the inner ring out and wear them themselves, apparently they do stay on thought not everyone likes how they feel.
Oh, with the Avantis, I found that it was more difficult than with latex condoms to put them on without trapping air in the teat. It could be that there wasn't enough care taken with that, causing them to break.