Actually my experiences with step-parenting are on a variety of levels all of them pleasant experiences.
My step-mother raised me since I was 2 yo, she is the best mother I could have ever hoped for but there was a disconnect that showed especially when my younger brother was born. I do not have any resentment of that, as I think it is very human.
I have participated with an ex in step-parenting his son, who I loved just as much as my two children, but really began to appreciate the suddle differences in the thought processes of parenting my children and parenting my step-son. That didn't change the love I have for him and he is still in my life.
My children are being raised by a step-father and while I know that he loves the children there are a variety of differences I see from how he looks at our vacation plans. We always plan trips for us and for them, but we have an ample ability to plan and vacation often.
I would never assume that because there is a hidden resentment it is a bad thing. It is a human emotion. That is why I wasn't meaning to offend.