Advice wanted on navigating relationship issue between DD(4) and SO

I have two daughters (3&4) to my ex partner, and SO and I have a baby son together. My eldest DD adores SO but he for the most part finds her annoying and does not return the same love and affection. I feel like I am doing her a disservice by being with this man and wanting to keep him around for the rest of my life when I see the relationship between them isn’t on level ground, and I am worried about the impact this could have on her development and the future dynamic of our family. SO loves son, and wants to be a family, but SO finds it extremely frustrating to be around my eldest DD for even half a day.I am torn between staying for the sake of my son and SO, or leaving for the sake of my daughter. Are there any other options for us?!All advice is welcome! via /r/Parenting https://ift.tt/2J9SX2A