Yes you can...It's so easy to change and shape human behaviour. Example is the Milgram Experiment...but anyways...
Has it been a while since you last dated someone?
You can actually shape your behaviour over time. Basically you do have dormant feelings for him, hence the jealousy. You currently have something conflicting with that feelings. Something is covering it up so you don't have that spurts of endorphins when he does something sweet or whenever. Do you perhaps had a crush on someone? Before the relationship? During the relationship? You might just need to get used to the fact of the two of you together, since you actually friendzoned him. When a guy breaks free of that horrid zone and the girl finally opens the door, it's a bigger change than people actually realize...
Your romantic and lovey dovey feelings will come.
