bandaid friend
A short-term friend who helps others feel emotionally better. When they've done all they could (usually with success), they exit the other friends life. This short-term friend is kind, helpful, a good listener, and can make any sad friend feel better. This "bandaid friend" can be mysterious, and may be reluctant to let other friends come close confidants. They're very approachable on the outside, but an introvert on the inside. These bandaid friends mean the best, and have a heavy heart for people, whether it's for the underdog, or just a sad person who needs to talk; meaning they're great with secrets.
I'm your bandaid friend, it's what I do.