I know I'm gonna hurt him

Most relationships end with someone getting hurt, I'm not even in a relationship yet, but I know he cares about me way to much more than i care about him. It's not that i don't like him, i do, he's pretty cool, and cute and pleasant, but he's already really in love and we only saw each other in person once. I like him and do want to have something with him, but i know that I'll be the one who'll get out ok and he's the one who will have to battle to get over me, because he already sees a future with me while i don't think we'll last more than 5 years max because I think I'm gonna move to another country and don't think my first boyfriend will be the person in gonna marry. It's just that he's cool and i like him, but i know it'll not end well for him