Your post is hard to follow, but I think I understand what you're asking.
It's good if you have an idea that you really like, but I also think it's important to be able to detach yourself from the idea. If the idea is naturally changing itself from one form into the other, try to put aside any personal attachment and ask: is it changing for the better or worse? It might be that the new idea has the parts of the old idea that you like, but also adds something else you prefer. Maybe it discards some part of the old idea that wasn't very good.
I think this is a relevant interview for the discussion
Between the 35 minute to 50 minute mark, the topic of leaving projects behind comes up. There's nothing wrong with taking an idea, working on it and doing something with it, and then just stopping. It might be a really good idea, it's probably not the best idea you'll ever have, and it's definitely not gonna be the last one you have. I think it's good motivation to know that you haven't yet had your best ideas. But if you get stuck on the same idea for too long, you end up stalling when you could move on to better ideas.
Also, I'd recommend listening to the whole interview. I think it's pretty good, and Psychicpebbles has some good insight into working creatively.