In my case, I gave my all to her and I accepted what little I received in return. It was unrequitted love, in a friendzone. I treated her as my family when she pursued other boyfriends. I eventually migrated away giving less time, but would still give my piority. The challenge is I don't see it with anger, it was what I was programmed to do... devalue myself, so it felt right. Now with the help of my girlfriend, I'm out of that and see it better, but the feelings... those are hard to process.
Did you get angry? write letters? just move on?