Is it normal that i'm grossed out by having sex during my gfs period?

My girlfriend is really into having sex during her period. I guess she is one of those women who get the hormones boost...as well as irritation and constant bitching. I get the box set...

Well I'm a little grossed out by the whole fact of having sex with my girlfriend while she bleeds out of her vagina. Matter fact I have never ever met a girl who thought that might be a good idea...When I asked my girlfriend if other guys she s been with had the same attitude towards the issue she told me that not since high school...um ok...I mean I have guy friend's too and I don't recall them being all about it either. We did however had sex on her period once, it was really messy and I had to take ANOTHER shower to wash the blood off my pubic hair and my dick...

Anyway we haven't done that since. She also refuses to give me head during her period under the excuse of "if I dont get anything you dont either, we both suffer"...word! but whatever i guess i can live with that even though i dont think i should because i dont believe my girlfriend understands the basic concepts of sexually satisfying her man.

But that's all not a big deal, what a big deal is is that my girlfriend gets MAD if I refuse sex during her period. She comes onto me really hard, telling me she wants me, acts all sexy and then when I tell her that I'm not down she gets all pissy and makes a scene...saying how it's fucked up that i say i love her and wouldnt put up with a little blood....or there is a good one...ready? I'm never giving you head again because if you cant deal with my natural issues neither should I...meaning my semen.

So I'm confused. Is it normal that I'm grossed out by having sex with her on her period and it's irrational for her to get mad at me about it? I dunno what to do because she holds grudges and it's something i have to deal with all night.