Female dwarf hamster fighting

Question
Six months ago i bought 2 dwarf hamsters (1 male and 1 female) Yes they did ''play'' fight but nothing serious. They shared everything and slept in the same little house. Now, just last night i had to seperate them as the female has started seriously fighting with the poor male. He is bleeding a little on his genitils and is a nervous wreck. My question is .... WHY???? Can she be pregnant and just trying to protect whats hers?

Answer
Dear Lauren,
thank you for your questions.
Dwarf hamster are social in the wild, but in captivity it's hard to keep them in pairs or groups. They will fight in many cases, even after living together for months or years. In the wild, they have huge territories and can avoid each other completely if they want to. They can also change and choose partners and the female does not accept just any male.
It is possible that she is pregnant, but usually the male stays with the female and even helps with raising the babies. I don't recommend trying to introduce them again, that will almost certainly not work. If she gives birth, you can try to introduce the males to their father when they are weaned so that they have an adult to learn from.
I hope I was of some help to you
Jennifer