a boy and girl can’t be together because of their families, because they have powers or something

i read it as a kid in elementary school in the early 2010s from my school library, even though i actually think it was in a teen section. a girl sees this guy who she’s never seen before (i think?) and they start talking and fall in love (there might be a pool scene at one point?) but her family and his family disapprove of the other teen and they don’t know why. she overhears a conversation about his family and their powers. they also mentioned a family crest that meant something.