Can someone explain

They didn’t even date but I think the ex was kind of manipulative but maintained that holy maiden persona

Ohh i did get that feelings when reading some of the panel and thought i was reading it wrong. Thanks info

It's just the impression I got, I think the timeline was pretty messed up and the time jumps made it hard to understand. I think it also could be that the ex was leading MC on. Since MC had an obsession with becoming a real alpha for him and really loved him, but in the end the ex left him and never had intentions to date him. However, there was also one scene where MC was acting like a scum, saying they were sex friends after they had sex but tbh that was reasonable conclusion

I think if u look at it all together once u've read it kind of comes together. The time jumps are like plot devices god knows why we don't need them

When he met Della, it dawned on him that the appreciation he receives for his art doesn't equate to appreciation of him or an indication of love. Which is something he mistook the ex for doing
The ex seemed to just go along with the offer of becoming fwb, but after a while of doing it - when he asked "what they were to one another", I think he expected a more committed answer than "we're just fwb" because he decides to leaves immediately after and grows distant.

You see Daymon struggle with that later on when he's asked implicitly to commit to Colton in which he's afraid to repeat the same noncommittal response but finds it difficult still to trust and so in his mind, he'll just be repeating that same mistake regardless because he's too guarded and committing is scary.