Why is My ex like this?

we broke up years ago but we still hang out. And he still takes me out to denny's or buy's me lunch at Friday's, or takes me to the movies. Im not that smart, so when it comes to stuff like when i have a terrible blonde moment he notices. And it's scary for me and embarrassing. Anyway's now it's awkward silence coming from him. He's alway's quite around me, and very non talkative. I wonder all the time what he's thinking. I'm usually the one talking, but then i stop and get quite and it's awkward. He still continues to buy me things that i want like ciggs exc. I wonder if he feel's like im dumb, or if he's annoyed with me or if he's always this quite and awkward. what do you think? ive known him since i was thirteen. he's 23 now and im 18 four mor months and my birthday comes. Is it because He's a pisces and im a leo or is it because of the age difference? we've done so much toghether and he makes me happy, and i think i make him happy cause he still hangs out with me even though we've broken up, and were not good together as relationship wise? i don't know why do you guy's think he's acting this way? i need a lot of answers cause im soo confused. and i don't want this silence and awkwardness to continue on i just want us to be happy as friends. Hes like the best guy friend a girl can have