one: He wants reassurance, that hes better than your ex. Low self confidence or maybe feels threatened by your ex, is he still someone you see around?
two: Let's not beat around the bush, you know it...he's embarrased. Whether, he's embarrased of his mates and how they might act around you if they come over because they've seen him (most likely, as lads [not sure bout girls] do act differently aroung their lad mates than their girlfriend, and so if they come over and act like dicks, you might think he's a dick)...or he could be embarrased of you, and doesnt want his mate to see, although this is unlikely as his mates probably know he's going out with you, and know who you are. Do they?