Is it infatuation or love when your boyfriend goes on holiday with his mates and comes back and tells you he missed you so much and says strange things like he kept seeing girls with the same hair colour and style as you, and it helped him to feel 'connected' to you?
I suspect he was so pi55ed and high on recreational drugs that he thought you were actually there.
The guilt part is that after getting his leg over with all of them, he realised they weren't you. I s'pose you could take it as a compliment if you like it like that.