I have / I had a couple GF's into it a long long time ago. It is nice-need a towel on the bed but it just a little bit of blood usually---can even still do oral since that is mostly tongue and clit.
I think a lot depends on the woman and what her cycle is like. Some have large tummy pains and it isn't a feasible ideas and others not so much making it feasible.
If you worried about the guy's reaction to bleeding, don't be/ you won't find a guy who is put off by that.
I hope you have fun taking care of yourself on those days.
