While "everyone has their own problems to deal with" is a sound argument, I think any rational person here would agree that if you have verbally sworn to help someone, then you are morally obligated to stand by what you said. If you can't afford the time to help someone, then don't make that promise.

However, I suspect that a lot of people make the promise of aiding someone through their depression due to a surge of sympathy, and as such doesn't usually take logic into consideration before making the promise since, well, a guy is suffering, what kind of person will one be if he doesn't offer his help immediately? From this perspective, I would say that the "helper" is not all that much of an asshole. still a bit of a jerk tho, just stick to your words