In my experience it's either a single thing, or both partners have similar situations and are each doing colleague things frequently. What absolutely does not

In my experience it's either a single thing, or both partners have similar situations and are each doing colleague things frequently. What absolutely does not work is when one of them is home pregnant and the other one is playing games with his buddies most nights at the gamedev shop they work for :). That is why I left a AAA game company. Had I been single, I would still be there. It was nerd paradise.