They aren't wrong. I was raised by a single mother. My dad was a significant part of my life, so i won't say i never had a dad, but I basically visited him during vacations only.

Because of the economic depression she ended up having to move around 3 times during my highschool period. It absolutely ruined me. I had a long term girlfriend, I had tons of friends. All gone. I started to develop relationships at the second highschool, and got uprooted a second time. I think it's one of the worst things you can do for a kid, especially if they are popular and have long term friends/girlfriends.

Having said that Nathan is not in highschool. Doing this in middle or elementary is literally nothing. I changed schools 3 times during elementary, once again because of moving. It didn't do a single thing. I could not have cared less, and had absolutely no long term impact on me.

Unless Nathan is in high school this kind of uprooting won't be a serious issue and people shouldn't give him shit for it, and definitely not the girlfriend in his life. What kind of person would blame the girlfriend and not the father? I'm not even just making a gendered argument, the PARENT of the child should take the most blame.