Yes. If you're asking this question, you have doubts and should go with your gut for a year. You're either in high school or fresh out and either he is the kind of loser who trolls high school girls like he wishes he could have back when he was age appropriate or he has a productive life as an employee or a student and wants you to be a part of it (though if that is the case, I can't guess how you met him, pretty sure guys don't look for recurring girlfriends at college parties).
Romeo and Juliet was written when the life expectancy was 50 and children were often married at the onset of puberty, so your analogy of fictional characters to a real life situation is somehow flawed.