Yeah, but I'm not sure you're following what everyone is saying
Sage being uncomfortable about it doesn't mean it's not official. She's not refuting that they are an item, she's specifically leaning into it, just taking it slowly. I see nothing that would stop her from going to meet with Neil and be introduced as MC's girlfriend. She might have embarrassment at the situation, because it's all new to her, but again, it doesn't make it any less official. (And just in case you're using it as a measure, you don't have to be introduced to a partner's parent/s for it to be official, either.)