crushes

I don't understand why people start taking advantage of you as soon as they know you have a crush on them, as if you had no feelings. there's this guy i'm talking to who at first was all sweet and nice, he even told me i love you but not as a friend or as a joke, he really meant it or so he said. This week i sent him multiple messages and he left me on seen like ever time i did so! But then he said sorry and all and i I forgave him, but then the next day he's AGAIN like that. I hate him so much now but he continues to text me. Can't understand his behavior at ALL!!