Boyfriend says he doesnt love me as much as he could?

He's a guy. You said you proposed to him? He's probably wondering if he should accept (unless he already has in which you should just stop reading the question). Guys (especially more younger one's) tend not to marry out of fear of commitment. Sit down and talk to him... and absolutely do not say 'I love you' until the end of ur speech. Again a commitment thing. The whole I LOVE YOU thing would probably make him feel worse. He probably needs time to mature. Keep your man and have faith... but if he drifts and further... follow your gut. You'll know what to do.