Menstruation

I haven't met a lot of men who are completely comfortable going down on a woman when she has her period. But some are. Most women are at their horniest before and sometimes during their period. You should definitely find a way to make her cum when she's bleeding, be it through fucking, manual, or oral stimulation. If you feel comfortable going down on her, great, it's perfectly safe. As you now know, you don't need to get anywhere near her cunt to make her cum. You may suggest that she insert a tampon, and then wash up. Or you could lay down a few old towels, turn out the lights, and forget about menstruation.