Married folk, is "happily married" a real thing?

I (39f) have been married for 17 years. It's hard, very hard. It feels like 95% of the time, it's work. We got married when I got pregnant 17 years ago. We don't have fun, we fight all the time. In those 17 years, we've changed so much. We used to have some things in common, but now it's more like I have my hobbies I do by myself, and he has his, there's almost no overlap.. I look forward to when he goes out of town so it's just me and my kids. Is this just how marriage is?