I'm going to be the creepy perv and say it out loud:
The fact that Aunt May is both younger and hotter in USM is probably the reason teen!Peter is handling it better than "adult"!Peter in 616 Marvel.
Who has 616 May hooked up with? Jarvis? Nathan Lubernsky, maybe? Fucking OTTO? Every single one of them, the definition of a sexless old man, made harmless and neutered by how obviously elderly they were.
By contrast, Ultimate May was married to Ultimate Ben, the ponytail-wearing, barrel-chested silver fox who not only looked like George Clooney's older brother, but also met May in a HIPPIE COMMUNE, in which, it is implied by Bendis in G-rated fashion, the Parkers might well have "swung." Follow THAT up with Ultimate George Stacy, who was in his FORTIES at the OLDEST, making May's crush on him a case of an OMG COUGAR ON THE PROWL, and teen!Peter would have to be pretty much BLIND not to see that his "old" aunt is basically the AARP version of Stacy's Mom.
Which, you're right, is terribly fucking sad, because it means that the TEENAGE version of Peter Parker is ONCE AGAIN more mature than the ADULT version of the same character.