Why do I still feel like this?

I’ve been off and on with this guy for a while now. One minute we’re official then the next we’re just talking. When he goes ghost on me he claims that he’s been going through stuff. My thing is if you just want it to be fwb, why not just say that? Then I would know what to expect. But he’d rather go through months or weeks of being consistent, hanging out and talking everyday for hours then to just stopping all communication. We haven’t talked in almost a month, which is the longest we’ve haven’t spoken to each other. I thought I was fine, like I really thought I was good. But today I can’t stop thinking about him and got emotional and started crying. I don’t know why I have periods of being ok to being sad about this situation. Is that normal?