I've had it at times. My married couples have even tried for baby autonomously a few times (Playing vanilla so not a mod).
I don't usually mind but one time my straight married male who was very faithful to his wife suddenly decided to autonomously woohoo with another male customer in the back of his retail store he was currently running. I can only assume it was a bug as never had that happen again, and I exited without saving so he wouldn't have the pink romance bar with anyone but his wife. He was supposed to be a faithful husband character so I was quite annoyed at him, haha!