How long should you wait for someone to fall in love with you?

I've been with my boyfriend for over a year (his second longest relationship so far). He talks about marriage and the future but he has not said I love you yet. I recently asked him if he loved me, and he said he wasn't ready to say it because he didn't feel it, but he has strong feelings for me. I asked him what that meant, and he said he didn't know, but he thinks about me and misses me when I'm not there. He has been in love before, and it has never taken him this long to fall in love. He has even been in love with girls he wasn't dating. What should I do? Stay with him and be patient? For how long? Or based on his previous history, if he doesn't love me by now, will it just not happen? Should I just move on? I'm scared that he will just settle for me in the end, but I do not want to be in a relationship with someone who does not love me.How long should you wait for someone to fall in love with you?
PATIENCE IS A VIRTUE, ESPECIALLY WHEN IT COMES TO TRUE LOVE.