<human>: Can you condense the text into three sentences or less?

I apologize, this is my first post and it may fail to meet your standards.

So, my cousin has a fiancée for about 4 years now. He's recently confided in me that their relationship is not quite as it seems. Apparently they are very open, as in, they sleep with whoever they want, whenever they want. But they do it under their own roof! I mean, She might bring a man over while he's home, and she'll bang him while he's in another room. Apparently it's common practice for them, and he enjoys it so much he'll jerk off just outside the bedroom door as she fucks a random guy in their own bed.

Here's a list of red flags that have appeared after they got engaged. For the record, they were a normal couple up until then.

-After they got engaged, she asked him to delete all FB photos of them together and to deny they were a couple. Then request that they can fuck whoever they want.
-She tells all their mutual friends that they are only room mates. He complies without any hesitation.
-He's very broke, and has been saving for a trip to japan. She ends up taking his japan fund and going herself to fuck random dudes.
-She moves across the country(Canada) to work and earns quite a lot of money. Doing so, she abandons the apartment they share forcing him to pay 800 dollars rent on his own, yet asks him for monthly weekly.

-Also, cousin seems to be a mental case with severe alpha male syndrome. What do I do?
<bot>: Cousin [27 M] seems to be being taken advantage of by fiancée[20something F]. Should I intervene?