I honestly don't know if they are fighting, but I have had a female mouse for a while, and I just bought a younger, smaller, male mouse. They keep jumping on eachother, and squeaking, and im pretty sure there not having sex because the female is jumping on the male, and unless they are trying to 69 eachother, I'm pretty sure it's fighting, My mail mouse keeps squeaking, like it's hurt, but I havn't seen any blood, and I have no extra cage to seperate them!!! please help!

Buy a new cage b4 it goes outta hand

Yeah you need to separate them she is having a territory issue and she will kill him because he is smaller. You could always put him in a box or something till you get something.

If they were fighting you would know. I'm not exactly sure what they are doing.

You don't need a new cage, you just need to separate the cage in two with something strong that they can't get through