My parents stayed in the marriage for the sake of us. We had to witness the fights, disagreements, and the overall lack of "love" in the house. When I grew up, I thought love meant "fighting" having "disagreements" and the lack of love between two people. As a child growing up, we learn from our parents. As a child you don't realize how much you have honestly absorb and will carry with you. So when I got married and the relationship was a split image of my parents, I made the decision for all involved to change that. I got a divorce, my kids are totally fine, and have moved on. We both have met someone else, and for me personally it's no where near my parents relationship. We show love, we are nice and sweet, and there is no drama with us in front of the kids. I didn't want my kids growing up like me thinking that love was to be cold and distant. I didn't want to be in a relationship for my children. As a child, I went to bed MANY nights hoping my parents would leave each other, and find happiness elsewhere.
Do what is best for all involved. You can't make her love you anymore than she chooses. It only lessens who you are when you are giving so much of yourself to someone who really doesn't want it. Teach your daughter what real love is about.