Should I feel some type of way?

Idk if maybe I'm crazy or being too sensitive. My boyfriend has kids from a previous relationship and I have two kids from a previous relationship too and we just had a baby of our own. My two kids their dad passed away. My daughter didn't really know him and she really honestly believes that my boyfriend is her dad. He's all she pretty much knows. I've been noticing that when my boyfriend's kids are over he give his daughter extra affection, extra attention and kinda just ignores my daughter. She just sits there and watches him be extra affectionate (non stop hugging, kissing on the forehead, cheek, always telling her he loves her) and looks like a sad puppy dog. I've talked about this twice with him already and he says he'll change, he promises he will keep it even between the kids but he doesn't. Should I be mad? Or feel like my daughter is just the "step child" that's not really wanted. Idk. He's super hard on my kids and let's his kids get away with everything. He shows them affection but not like he does his. I grew up in a family of favoritism and I do not want my kids to grow up around that. But he is clearly favoring his kids.