Has anyone ever had someone completely walk away and act like you meant nothing - only to realize it later?

I’m almost 5 months out from a really painful breakup, and I’m still struggling to wrap my head around how easily he walked away. One day he was telling me I was the love of his life, making plans for the future, saying he loved me and wanted to be with me forever — and then it was like a switch flipped. He broke up with me after a fight, erased me from his life, and never looked back. Not one word since.

What’s hard is that I wasn’t just some short fling. We had history. We knew each other for 10 years. We reconnected after years apart and got serious fast. Our lives were intertwined. We talked about marriage. We spent holidays together. He told his family he loved me and wanted to marry me. And now? It’s like I never existed.

I still check in on him sometimes (I know — I’m trying to stop). I’ve seen him following OnlyFans-type girls, posting gym and faith-based content, and surrounding himself with people who never really liked me — people who probably never gave me a chance. I feel like he’s rewriting the past, convincing himself this was the right call, and suppressing any regret. It’s like he’s totally fine while I’ve been stuck grieving something I thought was real.

I’m not looking for generic advice. I’m not even hoping to get back together. I just want to know:

Has anyone ever been in a situation like this — where your ex seemed cold, avoidant, like they never cared… but later came back, or admitted they messed up, or finally showed signs they did feel something? Even if it didn’t lead anywhere. Even if it came too late. I just need to know if that ever really happens.

I feel like I gave so much and mattered so little.