He sounds like a teenager. A dorky engineering student one with not a whole lot of manners or experience/background or guidance from any adults in his life, obviously.

If you aren't seeing him anymore, he and his arrested development aren't your problem. He has to learn his own lessons and grow up at his own speed. People have different sexual and other needs and it just sounds like he doesn't have a whole lot of help dealing with his from guy friends or other outlets. He's anxious and selfish. He probably has gotten the message that he can't treat you that way and that's the only message you're in charge of delivering.