I mean, if you're talking about shipping those two together, I'd still be sketchy if it was real life. But with fiction, It's a bit easier to be lenient with age differences. (What I mean here, is that a 15 year old dating a 17-year old and up can get weird, because that's the period when mental differences are pretty heavy. It's not as bad as if the latter person was older, but I'm always sort of wary.)