My guy has insecurity issues?

I think he has trust issues..so tonight we were talking about some things..you know one of those deep conversations..all of a sudden he was like "you better not slip up and run off with someone else". I asked why he think I would do that and he didn't respond..blantaly ignored it..how do I get him to trust me..and get over his insecurities..btw..I never knew handsome guys have insecurities..honestly..I'm not bragging..but he's pretty handsome..alpha male..beard..brooding eyes..teeth all perfect..smile will make you drop your panties in 0.2 seconds type of handsome..but it just baffles me that he has insecurity issues and not seeing himself as good enough. I try daily..but I think I'm not doing good enough; ideas on how I can get him to trust me?