sims that are married or in a relationship

Yes. I make sure my married couples talk to each other. I try to make sure my Global Superstar kisses his wife and says goodbye before he heads out the door to whatever activity his job calls him to. If he hosts a Fan Meet & Greet, he brings his wife along. They used to dine out fairly often, but that is incredibly bugged, lately. It may curb their habit. He also tends to his toddler children. He's not afraid to change diapers, either, which is good his wife just presented him with a set of twins.

Oh, and I play on autonomous, too. That way, it's nice to catch my Sims being sweet with each other all on their own.