I don't know why, but I assumed you knew each other a long time. Childhood best friends. It made the whole thing difficult to understand. Why would they do that to a long time friend? But it seems your experience was more like mine than I thought. About a year in length, right?
You know the people you hang with at school are hanging with each other after school. They text each other and call each other and go places together. Hanging with them at school is much better than nothing, and sometimes you even see them after school. As a group. You think you were invited because your presence gave them no choice. You don't really feel a part of their groups. And you're not talking to them one-on-one. Ever.
And then one of them actually seems like a friend. A couple grand, friendly gestures, even. REALLY grand. Lots of love language. You can text them any time. Call...not so much. And you know they're texting all day long, but yours...have to wait. Friendly...sometimes. Sometimes it feels like teasing.
And then...poof, they're gone. You haven't had a conversation in months. Answers to texts need a second prompting. Or are startlingly terse. Still...love language. And ghosting. How can you get both from the same person?
You wanted them to know you've noticed, but you haven't said anything. The best you can do is mostly ignore them on social media. They've done the same. So, you had little reason to believe they'd check in on you while they were in town, but you were profoundly disappointed that they didn't.
AmIright?