My boyfriend is distancing himself from me.?

He is making up excuses to spend more time apart. keeping more contact with his friends. More trips to the bathroom with his mobile phone....i know he is not cheating yet! less gifts, birthday or xmas. No sweet cards like there used to be! He always sys he is going to shop with his 'dad' or 'sister' when i call him, or making dinner and cuts conversation off! He keeps saying how most men of 28 don't have girlfriends these days, and there are plenty of single goodlooking women out there.It doesn't mean thay are cheap girls. what does this mean?