I feel this way sometimes but in the sense that I don't really care either way, I'm perfectly happy with the way things are and our life and get on well with the kids but if I were to be totally honest and truthful, I would prefer it if it were just DH and I.
I think I believe this because I do like our time when it's just us and it does make you think 'it would be cool if it were like this all the time'. As much as I like the children I don't think being a step parent really brings anything extra to my life that I would hugely miss if it weren't there I guess, not that I don't like it, but I wouldn't miss it either.
I don't dislike my SC at all, I really do like them and we get on great.
I know I married a man with kids, like I say I really don't care either way, I'd never leave and I'd never, ever be unkind to the children, just musing.