He isn't seeing his kids

My boyfriend and I have a 5 month old and he has 3 children from a previous relationship that lasted around 10 years.

He doesnt get on with his ex and now its affecting his relationship with his children. She tries to dictate when he can see them and things he should do with them

He seems so angry towards her and he just isn't seeing them or being involved as much as he should

He recently said that maybe they would be better off without him in their life.

I know he misses them, he was very hands on and involved when they were together, he says he misses all the everyday thing like walking them to school or watching them open their presents or making dinner

Should I intervene try and talk to him about this or is it not really my place