Just give her presents. Talk is cheap.

Yes. I would love to have more dialog options with wife (spouse), and kid. Right now, it's just too generic and feel like you are talking to a complete stranger.

I will play the devils advocate and say some people might find it nice and a chance to get away from the real wife talking all the time...

There are four types of female and four types of male partners, each with different characters, i.e. different phrases. It's not that few in total, but you can only experience the full range if you play different charakters/long enough.
Just more sentences would probably be boring again after a week, so new interactions would also have to have a meaning/a game mechanism.

By the way, which map are you playing on? In the Valley, there are significantly more interactions through the family quests that don't exist in Oxbow.

I remember when I started playing I picked flowers everywhere fully expecting to be able to give them to my (future) wife ingame, and was a bit disappointed that it wasn't possible.

I too would have liked more possible interaction with the spouse to make the npc feel more alive and less like all the other npc's.