This guy is lovesick for his ex. Normally that alone would be enough to put other women off but you've already hooked yourself on him and see him as a catch despite him being a pathetic simp (no man with a shred of self respect admits crying over an ex to another girl, or to anyone). My guess is, he's a betabux (guy with money who can't get laid otherwise) whose never had abundance.
Anyway he wants to play BF-GF, he's thirsty for relationship energy, and since he can't get that from his ex, he's happy enough to get it from you for the time being. Are you having sex every day, or more times a day? You're both still in the honeymoon period, look up NRE (New Relationship Energy).
He might even convince himself he likes you as more than just a fvckbuddy, but make no mistake, if his ex gives him another chance, he'll dance to her tune like the simp he is, and give you another "we're friends" and "delete me" pep talk.
He's already done it once.