You ARE an asshole.

Crushing a girl's spirit unexpectedly, probably destroying her image of her future, shredding her self-confidence, and ditching her for the only other person in the world she trusted and loved as much as you? Why would you think you'd be an asshole for doing that? You're way worse than an asshole.

No one should feel obligated to stay in a dating relationship that they’re no longer interested in. So that’s a mark in your favor. It also appears that you didn’t cheat and were honest with her. Also a mark in your favor. If you’re honest and not cheating at the time, and try to treat them well at the break up, you’re not really responsible at that point. BUT (and that’s a huge but) Ditching her for her then best friend, and thereby depriving her of her best friend as a support network and her boyfriend at the same time is definitely kind of an asshole move.

I'm kinda neutral with this FML. If you wasn't interested and you loved her best friend more (kinda scummy but shit happens), breaking up with her is kinda appropriate cause it beats cheating. If your ex hasn't found love there are many possibilities but we don't know the entire story of why you lost interest (thus we ask for OP to follow up for more detail to better understand). However, don't feel like an asshole since you left her. It creates turmoil. Just get over yourself and let your ex be.

The right thing to do is to break up if you’re no longer interested or whatever the reason as apposed to just cheating, absolutely. However, yes not everyone takes it the same. I know it doesn’t feel good to hurt someone but you can’t possibly expect to just never break up with someone only because you don’t want to hurt their feelings, this is toxic too. Relationships and love in general hurts, no way around it.

You know what they say - If the shoe fits...

you betrayed her and so did her best friend. that does permanent damage. she will never be the same as she was before. seeing you probably opened old wounds, she was not likely happy to see you

The great thing about life is every new day is a new opportunity. For you and for your former girlfriend. Maybe at some point you can share apologies, but learn what you can of this experience and go forward knowing that we can still grow

I think some of the responses here are quite subjective and come from a place of personal hurt. While it is true that you shouldn't ride rough-shod over people's happiness, it is also true that you can't be held responsible for people's continued inability to move on. Shit happens to us all. How we deal with it is up to us. There is a lot she could have done in 4 years to find happiness.

I mean, normally I would say it's not your fault that you fell out of love but ****** you left her for her best friend. You could have at least left her and then later got together with her best friend.