I mean I suppose it depends on where you live but here just having a relationship is usually fine, it's when it gets intimate (specifically sexual touching) that it becomes illegal. Definitely a hard sell to people not involved but it's not the worst.
On another note, mc should have really told that bitch off but he's a better man than me. Also why do there have to be so many problems, I really just want to read a story like this where they can actually just enjoy each others company and have a good time, instead it feels like they are in a tv show where it's everyone's business and there are constantly "new foes" to conquer. Kind of annoying, probably gonna drop it.