Take my opinion w/ a grain of salt b/c I haven't read YA fiction in about 10 years, but the last one I did read was the 3rd book of the Twilight series. But hey, I read fanfction, so does that count?
On the one hand, yes, teenagers (male and female) can get quite obsessive over their love interests...either to a disturbing degree (in which that YA rating may go left very quickly) or to a degree that many of us can relate to (as in, we look back on how frickin' embarrassing we were and can't help but cringe and try to bury the memory until the next trip down memory lane.)
On the other hand, there's a significant part of our teenage population (I believe) who are much more mature and much less trope-driven than we get in some fiction. Yeah, they're still gonna be young, dumb, and over-dramatic sometimes, but I think some people want more from their characters (female protags especially) today. Like... Marinette from Miraculous Ladybug, maybe? Girl's stalker-level crazy over a boy, but we can see her still living her life, doing the world-saving bit, how passionate she is about fashion and pursuing other goals, etc. So even though she's an obsessive nut, viewers are able to overlook it and fall in love with her because she's more than just an obsessive nut.
Honestly, I'm just happy* when female protagonists don't turn into either a Mary Sue or a Bella Swan these days.
TL;DR: What you say is true, but teen characters can be fleshed out more than obsession and rejecting authority and making horrible life choices a la Lifetime movies in order to move the plot along.