let me break this down for you:
Teens - no responsibilities. parents pretty much foot the bill for all of your needs. p*ssy is REALLY hard to get.
18-25 - you go to college and get a degree. you start trying to figure out your direction in life and career path. you go through several jobs to find a fit. get first apartment. you have an active social life and p*ssy is EASY to get because you are more confident. you STAY in the gym to keep your body ripped. gotta have the flyest clothes and the flyest whip. you MIGHT get a girlfriend, and if you do, more than likely you will not take the relationship seriously AT ALL. it will be more like a guaranteed piece of ass than a committed relationship.
26-29 - you finally find the career/job that will maximize your earning potential, so you plant your feet. you start a serious relationship. maybe have a kid. you start taking steps with your s/o to build a life together. get married, buy a lil house or condo and travel. You still are in the gym faithfully. but your social life starts to taper off a little bit. you are more into things that will make you money. but the allure of the nightlife still calls you, so you and your s/o bump heads because of it. you have single friends and they are still out there and the grass looks greener on the other side. this is the the "cheat on your s/o" phase. sex with the s/o is still off the charts, but you still find you a jumpoff and cheat. s/o finds out, ya'll fight and probably separate. then you realize that you love her and you try to get her back. she gives you a second chance. then another kid comes.
30-35 - career is going well, money is coming in. you got a couple of promotions on the job, so your money is SUPER STRAIGHT. kids are growing up fast (middle school/high school age). you absolutely ADORE your wife and you show her all the time. 401k (or 403b) looking really good. bank accounts straight. you start upgrading the interiors of your house (or just buy another house that's upgraded). your once single friends are all married now, or on the verge of getting married. your social life consists of outings with the wife, activities with other married couples, traveling with the kids, and the occasional trip with the fellas to somewhere trendy. you start to get comfortable with your life and relationship and start
good and you let your physical appearance slowly slip away. Then you realize one day that you gained a few lbs and you run back to the gym. wifey gains a few lbs too and becomes insecure. sex with the wife is still pretty good, but you start to look at that 21 year old ass and wonder why your wifey can't have one of those again....
36-40 - kids become self sufficient. they are in high school/getting ready to go to college. you spend a lot of time prepping them to start their adult life and participating in all of their extracurricular activities. all of a sudden, those few extra lbs don't matter that much anymore. you just exercise to keep your blood pressure/cholesterol down. sex kinda tapers off because you and your wife are just too damn busy with work and life. Money is stacked up in the bank and you can pretty much do anything you want to at this point. you start buying lil BS cars for the kids. giving them money for school trips. you still go on date nights with your s/o, but the places get more extravagent. expensive restaurants, jazz clubs, quick overnight trips in swanky hotels. cars become more expensive. clothes become more conservative, but equally expensive. you rarely go out with your friends anymore, and you don't really care. if they wanna see you, they can com and hang out in your man cave and watch the game with you. your bar-b-que game is RIDICULOUS. everything just evens out. you are generally content with the state of everything. This is also the time where your relationship with your s/o can get stale. People usually will step out again during this period. Gotta watch out for complacency. but other than that, things are normally pretty chill around this time in your life.
There you have it.
this is bullshyt
I dont know to each its own.My point was their is a window for yall 
you're not always this confident in your life/relationship
i don't need convincing. you read one thread about an issue with my wife and now i'm not confident in my life/relationship? just because i hit a rough patch with the wife doesn't mean my life is shyt. and my wife and I are good now. and even if we didn't recover, that wouldn't change shyt about my life. i'll be straight regardless.
fukk outta here....
i was generally speaking. none of what i wrote is exact....
in a few years time. 