my ex from college stands to be my best relationship. everything was awesome. we never fought. we were good friends and great together. i still wonder if that could have been more, but we were both younger and he still has problems with the future, so who knows.
one of my very good friends and i have a lot of love for each other, but we've never actually dated. we've talked about it and we're alright with never dating. sure, i'd still love to have a relationship with him, but when weighed with possibly losing the friendship...i don't know. i guess he was the one that got away...kinda. haha
i don't think that it's bad to think about it though. only if it ends up destroying your relationship. that's when it's bad.