The only lows I had with my step-daughter were years ago when her and I were new in our relationship. I did resent having to take care of her every weekend she was at our place because he was working. But that was only a few months.
We became very close and in fact, during the years we lived apart, I had her on his visitation weekends. Not out of obligation, but rather because we wanted to be together.
She is now a beautiful 22 year old woman, who amazes me always and has for years. She has just indicated that moving forward she would rather see me and her brother, without "dad" there. Someone in her dad's family would like to meet her and she told me she would not unless I facilitated it. She only wants me there.
I am so humbled by that and so proud of myself for doing almost everything right for so many years and the fact that she is the only person who sees it doesn't bother me a bit. It is because she realizes it, that is what makes it all worth it.