A friend of mine has been separated from her husband & father of her kids for 2 yrs. Kids are 3 & 5. They did ivf in order to conceive both times as her ex was infertile so they ended up having to use donor sperm. I think they always planned to be open about it with the kids but haven’t yet as they’re still v. young. Donor was anonymous (to friend & ex). They’ve shared custody pretty evenly for the last 2 years but the other day my friend says she’s sick of her ex causing problems and being difficult and wants to try and get full custody of the kids - her reasoning is they’re not biologically his anyway so they belong with their biological parent. They’re both on the birth certificate. AIBU to think this is pretty unreasonable of her and cruel to her ex? Pretty sure he sees himself as their father and he’s been there for them since the day they were born. He’s a good dad as far as I know, although he does make life difficult for my friend..but that shouldn’t be a reason to try and take his kids away should it?