<human>: Can you provide a brief rundown of the text in within 3 sentences?

Backstory:

Me (F 20) and him (M 21) have been dating for 18 months. He is my first boyfriend and I am either his second or third girlfriend, but so far, his longest relationship. Sometime last year we said "I love you" to each other, but then both decided that it was too soon and took it back, but he initiated it the "takebacks". Since then things have been pretty good with minor ups and downs like all relationships have. I let him be the one to say "I love you" first this time in an attempt not to rush him into saying something he didn't mean. However, now another couple months later, after 18 months of dating, I noticed he hadn't said "I love you" in a long time and I asked him about it. He told me he doesn't know if he loves me. Is it normal to not know after 18 months? He says he doesn't know what it means to love someone and that he thought he meant it when he told me. 

I honestly feel like I love him, but don't know how to describe to him why I feel that way. He's a very caring, funny person and I really enjoy spending time with him and seeing him happy, however, he doesn't know if he can ever love me...which worries me. I'm also afraid that the next time he tells me he loves me (if he ever does) that I am not going to believe him. He told me he feels uncomfortable when I tell him I love him so I feel like I can't express how I truly feel about him. The whole situation hurt my feelings and he knows it (I cried), but still remained honest with me. 

Another problem that I have with him that I'm considering to be a small one at this point is that he doesn't ever see himself getting married…ever. It has nothing to do with me and he doesn't know why he feels that way. He just thinks marriages are stupid and that they all end in divorce anyways (his parents are still together btw).
<bot>: Is it normal to not know if you love someone after 18 months? Am I overreacting or am I wasting my time with someone who doesn't seem to know how to commit?