Ive recently learned just how many relationships my ex has been in, some of them even being with my friends that i had no idea about. This is the same for most others that i know. Being 16 and going through mental changes might have something to do with the fact that others jump from relationship to relationship so quickly, but it just doesn't feel right. I definitely could not handle another heartbreak like i did before. That time i almost killed myself because it just added to all my mental health problems. 

So why is it that i just cant understand how people do it? How they can seem so un-caring about their relationships, and move on so fast? 

Maybe this is normal and im overreacting, but something feels off. Can someone please give some advice.