Why does he do that with his new girl, but never with me?

I just got out of a 4 month relationship, a little more than a month ago. My ex got a new girl excatly a month later. He kisses her all the time, picking her up, and just a lot of pda. I do not care they go out. I have no jealousy at all. I just feel ugly, like was I not good enough for him to sow all of that pda with? I mean we kissed a lot and everyone knew we were together, but we never did a lot in public! I feel kinda ugly. What do i do?