It's just like blood from your arm-period blood isn't like fresh blood as it formed a lining in your womb for a few days(as I'm sure you'll know) whereas breaking your hymen is like breaking any other bit of skin. There won't be much blood (hopefully) and it will be painful...But I'm not sure how painful, as my hymen didn't break during sex/foreplay. I think a tampon did it or something. I never even noticed. How sad.