At this age, our friends will have their own partners, they get upgraded, they change status, they have different priorities. That's totally fine and normal.
Then, you have someone, who vanished from thin air when they get a bf/gf. Okay, I'll give the honeymoon period of 6 months. Non-contactable of 6 months is actually non-acceptable but I'll try to be understanding, the max is 6 months. That means, not a meet up, no calls, no messages, nothing.
They just, disappear. When they were weak and down, people were there to pick them up. If you have been talking to someone, or to some people, I think it's only right if you tell them that you got someone and you will be seeing less of them. As friends, I'm sure they understand. But, without a word when you have been talking to each other every single day? That shows how much respect you have for your friends.
After a year, it is safe to conclude that this person will not be reaching out to you anymore, ever. It's best to just remove this person from your life because that's what they asked. We, as human beings, just reciprocate what they have done. It's okay, karma won't get back to you. Instead, it will be to that person who is unappreciative for what you had done. People love taking others for granted. That includes, people, who may or may not be your friend. That's how people are these days.
Sometimes, you will just wish you weren't there when they were down. *pats back* you did a great job. Don't worry about that. There are so many who are appreciative *proud smile* It's all good and in the end, it's worth it. Those that don't, when you fall again, that's because you deserve it. You'll suffer much more than how you did. haha.