Is my bd talking to his sister weird!!!! Plz read

(Edit - I just want to add we’ve been together almost 6 years, we don’t go out anywhere together, he is not interested in going anywhere with me or our children. He does not do anything family time related with us) but when he’s at his sisters house he goes everywhere with her and even went to his nephews karate class with her. Mind you I can’t get this man to even go to the park with me and my kids, ever!

I have a genuine question I feel I have to explain the situation and ask for opinions because I know I’m not trippin!

Is it weird that my kids father talks to his sister for hours & hours. Like I’m talking about for hourssss all hours of the night from 9p.m to 2a.m just be on the phone talking about the same dumb shit. When I ask him how long he gunna be on the phone it’s an instant attitude. When he has an attitude about ANYTHING he will ignore me all day or night because he’s mad & the first thing he do is get on the phone and call his sister. He acts like that’s his girl and she act like he her bd, he don’t call me when he’s away or sit on the phone with me or his kids for hours! My kids practically beg for his attention & don’t really get it but he can spend hours talking to his sister???? 🤔 If I ever called my brother and stood on the phone with him for hours he would tell me I was “fucking my brother”!! Me and his sister do not like each other, he calls her and talks shit about me every time he’s mad. But like am I bugging fr for feeling some type of way? Y’all think that’s abnormal the amount of time he spends talking to her? That shit is weird asf to me. . .