A: He was probably venting. Your boyfriend is probably the type of guy who doesn't express when things bother him. He keeps bottling it up and he popped.
A: My fiance does the same thing and it even got bad where she couldn't sleep at night so now she takes a bath/hot shower to relax for about 10min before bed
A: Doesn't bother me as long as she says something before I go down there with my mouth. She usually doesn't like to have sex while on her period anyways though.