I see this final line as something she's speaking with the benefit of hindsight, she likes him now, no doubt about it, and she wishes the situation she currently finds herself in wasn't so complicated... she wonders if him staying would've been enough to uncomplicate it.
At the same time she recognizes that had he stayed, their current relationship probably wouldn't have played out the same way...
He was 13, looked like a kid and she was 16 close to a young adult(and, again, she expresses being unhappy with the kiss right at the moment), they didn't have much in common(Erynn also says that during their fight, that they never talked much).
Heck that was the thing that was scaring him about "losing Erynn", she was making new friends, her own age, and didn't have time for him... that applies to Alexis too, though he wasn't concerned about her at the time.
Her level of indifference vs actively wanting him to stay (at that particular moment, not right now where she clearly wishes he had stayed) is always going to be speculative and biased vs objective.
I do think this kiss meant more to her than to him, since she remembers everything and connects the dot much easier and he needs a biiiiiig push to remember her at all.
Maybe you will find my take overly negative(like i find yours positive) but it is what is...
PS: I think we got off on the wrong foot, but i don't wish any ill will upon you and i think this latest post was very well reasoned even if i see it differently
