My mom hates the boy I love

Okay so there's this boy I've been talking to off and on for a little over a year and a half. He lives in a different state and I met him at my cousins church so I see him maybe 2-3 times a year. This boy has a history of kind of finding girls he thinks he likes then realizing he doesn't and then he comes back to me and I've forgiven him every time. But the most recent time was in the summer. He basically tried to date my cousin (who doesn't like him at all) so of course she said no then called me. We stopped talking after that. Then about a month later we start talking yet again and we decide to just wait until I graduate to try a real relationship and until then just date other people. Of course I agreed because I love him so much and it'll take the problem away of us trying to not talk to anyone else when we're highschoolers living in two different states anyway. But when I told my mom about his proposition all she had to say about him were hateful things. And she's never even met him. This scares me because if we ever get a serious relationship I don't want her holding grudges over things that happened years ago. Help?