What is he trying to do?

well it sounds like he doesn't want you to move on from him. honestly. he's jealous because he hasn't found anybody yet. that's a LONG time to hold a grudge against you! 3 years dang. he probably does still have feelings for you...why would he try to sabatoge you? but idk if he wants to be with you still...if you feel like you should, talk to him about it. good luck.