Not my relationship but...

My little brother in law has been in this relationship for a little over a year, we only met this girl about six months ago and no one is crazy about her. She immediately started to try and call the shots in our house when they were staying with us, my husband and I put an end to that right away. But she still talks to him like he's a dog that needs to punished, all the time. They are always together, like she literally follows him around the house, bossing him around. And yelling at him about the simplest things. I really want to ask him if he's genuinely happy or just looking for some to split the rent with, & has no other option. Cause to me his face says, "I'm miserable" when she's yelling at him about whatever has most recently pissed her off.