Your fiancee has a valid point in that the normal world works M-F and most socializing/family quality time happens over the weekends, and particularly weekend evenings/nights. If you're insisting on being absent for that even with kids in the picture, that's being too rigid.

That's how my first paragraph should've read, sorry. If I were to put myself in your fiancee's shoes, my concern would be that there might be a lot of adjustments and unforeseen incidents that might come up simply because your work schedule goes against the grain of how our society functions. It's possible to plan for it but might be tedious and constantly having to account for such an unorthodox lifestyle might lead to mental fatigue.

But then again, you made it abundantly clear right at the beginning and she agreed. Hence my ESH.

But in the end, are you willing to lose her/this relationship over this?