Why does my boyfriend act like this?

My boyfriend and I have been dating for almost 6 months. When we first started dating, he always wanted to see me, & talk to me. he would constantly ask when the next time he'd see me was, he'd text me cute things in the mornings, & talk to me on the phone before he went to bed.

Now it's like everything has changed. He barely wants to see me (but he doesn't want me to hang out with certain friends of mine, or any guy), he barely talks to me during the day, he'll make plans with me (but then he'll turn around and make an excuse for us not to see each other), he'll text me in the mornings (but only a "good morning", not bad, but not what it was), and he never wants to talk to me on the phone, or any other way. it's like he's become someone i don't even know. i haven't cheated, i haven't done anything wrong. i know this.

maybe, is it time to find a new boyfriend? i've been debating on this for so long... sometimes things get better, and they go back to normal, but i can not take the flip flop anymore. i've become completely emotionally exhausted, i'm tired of being unhappy. advice, please?