I've dealt with this many times before and I wasn't even in relationships with these girls.
It's very easy for women to lose interest in you, whether you're friends or lovers. I've had female friends that would treat me like a celebrity. Always having good conversations, we gave each other advice, made me feel like family. Fast forward a couple years later, it's like we were never friends to begin with. No more conversations, and if there are, they're brief and generic. "How are you doing?" "I'm doing fine, you?" "I'm alright, so what are you up to?" Conversation ends there.
I swear, weeks ago, I got followed on Instagram by some girl I went to high school with. We never had a single problem with each other, we were always cool. And I didn't seek her out at all, she followed me out of nowhere. I message her, she replies, I reply back, and she leaves me on read. Haven't spoken to her since, the conversation lasted three messages.
I've learned (and still learning) that women treat you like a pop star. You can be the hottest thing in the world for a couple months or even a couple years, racking up hits. But once you fall off, or someone takes your place, you stop being relevant. They made you feel like the hottest thing in the world and they can also make you feel like a has-been. It's about who gets who first.