I think we have to be careful when we say it doesn't matter if someone is okay with something or not. It does matter.
Not every person is okay with practicing safer sex. Usually, that has less to do with them having done it and disliked it than with them never having done it at all, and thinking that it means someone doesn't trust them, or thinks they're dirty. Those of us here, of course, know that isn't so. Anyone can transmit or catch disease, and if you know how, safer sex is fun and easy.
So, not everyone will be okay with it. buit someone who cares about you and about their own health should be. If they aren't, in my mind, they don't care enough about you to share your bed.
As Lisa and Bettie both said, using a good condom, and a very thin one (around here we like the textured sort) with a few drops of lube inside is the best way to do it, and it hardly cuts on sensitivity at all. Basically, any oral sex is about the heat of a mouth, wetness, and pressure, all three things which are not taken away by a condom and lubricant.