Because of her age, a woman that I work with ends up dating men who still have minor children. And, because of custody arrangements, he has them every other weekend.
Now, this custody arrangement upsets the woman because he spends time with his kids instead of her. (Go figure) And, even if he tries to include her in the activities that he has with his kids, that is not good enough because she has to adjust her schedule to meet his.
If you find yourself in this situation, cut your losses and move on. His kids are a fact of life and her unwillingness to accept them won’t change.