Advice for a loved one

Ebony • 👑Mommy of 3 Melanin Queen..My Angel😇,,,My Princess&Prince,,New bundle on board❤️...Tax Accountant👩🏽‍💻📊📈...c/o 2018🎓🎓🎓
Hey guys my little brother is 29 he recently broke up with his daughter's mother they were together 5yrs and now that they are broken up he can't see my niece...her birthday was the other day he wanted to get her and do something special but her mother wouldn't allow it she told him don't worry about them they're good...the thing is he isn't worried about her he is worried about his daughter...how can you just rip a child out of a father's life??this is affecting him a lot he's so stressed about it and it makes me angry to see him hurting what could he do to get back in his baby's life???