My bf and "I love you"

My boyfriend and I have been together for going on three months, we talked for a month before dating...

The other night he told me he loved me but I kinda feel like he didnt really mean it because he hasnt said it since. He said it first and I know I'm in love with him so I said it back and I've said it one other time since but he hasnt said it anymore

What does this mean/what should I do?