I completely understand this feeling and it's really tough to overcome but does get easier as the relationship grows I promise! What you need to hold on to is things like how he greeted you when you got home from holiday! Hold on to the good memories to get you through those times of doubt - even play it a little cool and then when he does come around you won't feel horrid!!! He's a good guy :) don't allow your past to ruin that when you've been happy!! You deserve a goodun!