I'm not sure if you've played the last few updates, as well as other people who may be reading, so I'll put a spoiler here. He's already talked to harper and also thought to himself on another occasion about going to Lauren to talk about him being in a relationship with her, and Lauren absolutely adores him, so even though she will be hesitant at first, she will likely allow it under some conditions like, keeping it professional on school grounds for example. As far as Natalie goes, they agreed they would have to tell her, and she loves her mother and will want to see her happy, and she also will want to make the MC happy as well, she might be shocked, but I don't think she'll react badly about it. The Liz and Nat interaction is kind of irrelevant since Liz is the one who instigated it, Natalie doesn't seem like the jealous type, at least no where near the level of Liz. (although now that Liz is his girlfriend she's already seeming happier and less jealous, so probably won't be an issue anymore.)
So yeah, It might be a little shaky at times, and won't always be easy, but I don't think it will bother Natalie much if at all, and also I know Lauren will be ok with it, even though she will definitely be hesitant and give at least a couple of conditions in exchange for allowing it. As long as Both Harper and Natalie are happy with the situation, I don't see a problem with it.
