Why am I so jealous of my boyfriend's daughters?

Why am I so jealous of my boyfriend's daughters?
Probably because you want to spend time with him and you have to share that time with his daughters. My husbands little sister was 5 when we started dating and she was always wanting us to spend time with her and I would catch myself being jealous that I didn't have him all to myself...then I would feel stupid that I was being so juvenile. After awhile it gets easier, you just have to accept that they are a part of his life and make sure that you have time for just you and him every once in a while.
Probably because he give her more attention than you do that's all!
because he showers them with attention. thats how i feel with my daughter and my wife gets jealous
you might be feeling like he gives his daughters more love than he gives you. Maybe you feel like he gives them more attention than you. You might secretly strive for the same affection and attention that your boyfriend gives his daughters.