How to deal with a jealous S/O, help!!

I've been with my S/o for almost 5yrs and at 1st him being jealous I thought was cute now it's just gotten out of hand! Sometimes we go days without speaking to eachother because he's so jealous, either of me tlkin to other male friends, or going to parties etc.How do I help him get over his insecurity ? I've tried talking to him about but all he says is that he's going to try to do better! Help??