The male does not know that the female is pregnant. He will try to mate with it for as long as he can.The reason why the female is so aggressive is to protect herself.it will continue even if she has the babies. He may try to kill the babies in order to mate. Separate the babies from the father for a month or two. He will try to mate with them as soon as they become of 'mating' age
It is not normal for 1 male and 1 female guinea pig to fight aggressively. Are you sure that they aren't both males. Males can live together quite happily and then suddenly decide (even years later) that they don't like their room mate. If you are sure you have a male and a female, it is normal for the female to butt the male with her nose and chase him a little. She is saying she is not ready to breed. When she comes into heat, she will allow him to breed her and then they should be more friendly. Never should they be drawing blood. Also, the male is very paternal. He will help the female deliver the babies and will help to clean and dry them. They are not aggressive to their young. BUT, if left with his mate, he will breed her again within 6 hours of birth. - Very hard on a female.
