The key symbol in your dream is "cheating", which is an extremely common dream symbol. It often occurs because you are not getting from your current sweetheart what you want. It doesn't mean that you will or that you even want to be with another person. Here's a link to the definition on this website...
cheating:
dreamdoctor.com/component/dreams/?contro...&task=details&id=439
You aren't getting the attention you want in your current relationship, so in your dream, you found it with a "sure thing." Your dream is telling you that you want more attention from your current boyfriend. That's a hard thing to ask for... but you have every right to.
Hope that helps.
PS You might also want to check out the video that discusses ex-lovers in the "Listen Now!" section of the homepage. While your friend who had a crush on you wasn't an ex-lover, the reason why you are attracted to him in the dream (the "positive" example) may be explained in the definition of this symbol.