Your parents are very wise. No, it's not you.
Another good exercise at this point is to make a list of all the things that are wrong in this relationship - an actual hard copy list or a list on your phone and every time you start to ruminate about "the good times" pull that list out and review it.
Like anything, after a week or so the anger fades a bit and the bad stuff starts to fade and you can start to feel bad about the whole thing, refer to that list 20 times a day if necessary to keep that uppermost in your mind.
I think it's a good idea to be specific too, so for instance:
Instead of:
He is rude (although it's worth putting that on the list as well) you might want to write:
When we went out to dinner with friends he made fun of my room mate's story and insulted the waiter