The significance of being 25:
You are no more in the young, 18-25 age group; well almost... well, you don't feel like it. So step on to the next one - 25 to 35 - working, young professions, probably married, income (whatever), blah blah blah...
Ok these are the "marketing" terms... what else...
You feel too mature for the "18-25" and too young (not so wise) for the "25-35" age groups.
You actually start thinking (worrying) about your skin... wrinkles are a very close reality. Losing weight becomes even more difficult; you put on one kg from one piece of chocolate, so eventually you kinda start accepting it.
This is the prettiest you can be. Ever. You don't get any more good looking than this. So if you think you are not that great looking, well, then this is it.
Money becomes important, you might still be afraid to think about the future, so you think about money, instead. Career? hmmm.....
You start thinking of ways to keep in touch with your friends who will eventually get married hoping things won't change too much. They would. You know it.
You hope time slows down till you have to settle down. Well, you hope time generally slows down... And since the past (college days etc) is a fading memory of a different you and the future is uncertain as usual, you struggle to hold one in each hand but probably moving in some random, maybe diagonal direction. Well..... acceptance is something that settles in like some sand in water, some disturbance initially, and leaves it changed for good.
Sigh....