Children wake up, hold your mistake up, before they turn the summer into dust

Being confronted with the 5th ending of a LONG term relationship in my close circle of friends (all of them having been at least 7 years) in 6 months, I've now started to wonder WHY?! What is wrong with us?! Of course, now all being about 25, they've been together during a time of their life's when your peronality developes maybe as much as it will never again and of course there's the danger of developing into two completely different directions, but still, how come they've all broken up just now?!
For me turning 25 was a weird thing, because then you've officially ended the first half of the 20s and are now about to be on "the wrong side of 25", pushing on 30. But it is only weird because you don't feel any different from when you turned 20 or 21 and then you get to thinking that it will just go on like that and one day you'll turn 50 and still feel the same, which is a good thing on one hand, but on the other hand it's not, because you fell the same, but are regarded as "old"... But I'm getting carried away by the thoughts I've recently been thinking over and over and over...
To me it is also a weird age, because, although I don't feel "grown-up" AT ALL, I feel like I have to make descisions at this point in my life that will still effect me 25 years from now- I'm about to take my final exams, was it the right thing to study, do I really want to work in this job? All my life? Where should I apply for a job? Do I want to stay here near my family or do I want to go far away and totally start fresh?! Do I maybe want to live abroad?!
I'm really afraid to make mistakes, to make the wrong descisions and then live an unhappy life and regret them when I'm 45 and miserable. And I think that the issue is a similar one when it comes to realtionships...When they first started dating they were between 15 and 18 and everything was exciting and fun and when you imagined your future at that age you always thought "Oh, ONE DAY I'll get married and have kids", but the thing is that "one day" back then was so far away, intangible and now that you're closer to "one day" than ever before, you might start taking your relationship into consideration again, before it gets to a point where it becomes to serious and you can't seem to find a way out if it again . You start questioning the "plans" you had when you were 15 or 16 and it's all about making descisons again...Do I really want to get married one day? Do I actually want to have kids one day? Do I want to have a relationship at all? And again you're afraid to make the wrong descisions and that is why you are afraid to make descisions at all, because they could turn out to have been wrong...altogether I think it definitely is an akward, tough periode of time in our lives where you can get easily confused or overwhelmed and therefore start panicing and want to call a halt before it's too late...
Or maybe it was just coincidence and they had all grown apart from eachother idependently, but that still wouldn't make descisions any easier.
I just really hope things will turn out alright...