Aww OP, you sound bereft and i have been in a similar situation myself and i sympathise. I also don't think I'm obsessive or intense, but in my situation i did become those things as well.
He was narcissistic, exactly the same type of guy you're describing, the same trying to make me jealous, love bombing me then discarding. He discarded me in the end for a relationship with a girl he had only just met and said was ugly and whose personality he hated and it finally drove home that i must be even lower in value than that to him.
We were actually friends for 20 years but he was always too intense, i used to break contact for months and years at a time, then we slept together a couple of times spread out over many years and one day i suddenly found myself in love with him and wanting more. It was like a spell.
Anyway we haven't spoken now for years, it hurt for a while, i got therapy and now i realise it was the idea of what we could have been (in my head) i wanted and grieved, it wasn't him, because he was never that. So my advice is to reject the rejector. There's no relationship to grieve, you're grieving your idea of what you wanted the two of you to be, not him and you two as you ever were. Sure, he may have set you up to believe in it but he has rejected you. You can't handle that any other way than to reject him back, it just doesn't make sense to do anything else.
He will likely be back though. Don't play games, just ignore him and one day you'll meet someone that values you and treats you better.