My best friend's boyfriend help?

So my best friend has been dating this guy for about 6 months. The problem is he's still living with his ex because they rented the flat at the time when they were still dating and they have to live together until the lease is up.

He doesn't allow my friend to come to his place when his ex is home. Saying that it makes her uncomfortable???

They still haven't had sex yet although she told me he said he's very sexual and has had sex with his ex before and she's worried that he might still be banging his ex who lives together with him as he never initiates anything sexual with my friend. So she thinks that maybe he's getting it from somewhere else.

The other day my friend saw him and his ex together in the library and when she confronted him he said that they were studying but they're not even doing the same course in uni.

He said she's making problems out of nothing and that he needed a break because my friend is "very emotionally dependant"

Do you think she should break up?