I think it's very normal for you to be sad when he's not around..I'm going through the same thing but the relationship I was in wasn't healthy so I have had to remove myself from the situation..I love him very much so this is really hard to deal with, day to day. I normally spend every minute with him(for the last 2 years) and now I don't see him and rarely hear from him. I hope with time I can get past this..Good luck with your sadness.