He means that Andy has created an unrealistic version of Nathan in his head instead actually seeing Nathan for who he is. Andy is trying to 'catch up' with his imagination instead of communicating and being honest witch hurts them both because Nathan isn't the perfect being Andy is imagining him to be.
It's actually a complicated relationship if you do a proper breakdown and look at the individual characters perspectives
And that’s why they should communicate, express and talk it out slowly. But it’s realistic to not communicate well, and they’re both pretty young which makes sense.
I don’t remember much, but I think it was Andrew that wasn’t able to get his words out and “ran away” from communicating(?). And due to that besides the main reason, Nathan got upset and walked away.
Bro wdym he put himself on a pedestral.....for god's sake you're his first ofc he'd have like 100x worries