My cat is seeming less vocal and sleeping often...?

It doesn't really sound like anything is wrong to me. How long ago did you move in with the bf? Your cat may still be adjusting to the new home. It takes animals longer to get used to a new environment. Also, your bf has an older cat, your cat may feel more comfortable now that there is someone/something there with him all day. The loud meowing can be a sign of loneliness or hunger or just wanting to meow. I'd suspect that the cat is still adjusting or is more content now. Especially if he is still eating and sleeping normally to you. Just keep an eye on him for behavioral changes to diet or sleep or drinking.