Fall asleep
Often we look forward to married life as an opportunity to always have someone to do things with. We can go on holiday to all these exciting places together, learn a new hobby, dine out with a large group of friends, or talk late into the night about important topics.
What happens in practice, at least in my experience, is that you spend 3 hours trying to decide what you want to do until you fall asleep on the sofa. When you add kids into the mix you skip the conversation about what you want to do and replace it with “what do you want to watch on TV” until you fall asleep on the sofa.