Coming from a guy OVER 40 I'd like to provide a little input.
First, sex after marriage DOES decrease. As in immediately. Yeah, you'll get some your wedding night, but that has nothing to do with her desire for you. She doesn't want "No sex on the wedding night" hanging over her head for the next 40 years. You may even notice the a decrease in sex DURING the honeymoon. So, I would say MOST women use sex to get the ring.
Now, where I believe the OP is off. His analysis is great from a guys perspective, but look at it from your wife's perspective.
A married couples Libido is rarely in tune. When they're young, the guy wants it all the time, and after 39 the girl wants it all the time. (At least from my experience.) That natural imbalance will cause "issues" within the marriage, no matter how old you are.
What most guys don't understand is the following:
Periods
PMS
Urinary Tract Infections
Yeast Infections
Indometriosis
A VAST number of other things that go wrong with women parts.
Your LAZY @ss stopped courting her after you got married.
Your LAZY @ss sits on the couch while she does all the house work.
Exhaustion from work.
Since she most likely has a weaker libido at a young age ALL of the above factors figure into her desire for sex. Most of these issues have NOTHING to do with you.
Then along comes the baby.
Underscore
EXHAUSTION on the above list. And add "Baby Weight", and a sh!t load of other issues that go wrong with women parts. She no longer feels sexy, because she has lost her figure, and her t!ts have started to sag.
HOW YOU PARENT YOUR CHILDREN HAS A DIRECT IMPACT ON YOUR SEX LIFE
Here's a BIG KEY to raising healthy children, and having a healthy marriage.
You have to set the FRAME.
As a couple, you have to agree that the child will NOT be the center of the marriage. You as a couple are the marriage. This will help the family in a number of ways. One, the child won't grow up as a "Self Centered Brat", who believes the world revolves around them. And Two, what happens to the marriage after the kid leaves the nest? A child centered marriage, will most likely fall apart, whereas a couple centered marriage will continue to thrive.
A young child will find comfort in the fact that Mom and Dad date and flirt with each other. Unfortunately, a toddler is too young to understand. Part of parenting is prioritizing YOUR relationship OVER the relationship with the child. Which means you will need to spend couch time with your wife, while the little brat is throwing a trantrum on the floor, because you won't pick him up. However, once they understand "couch time", they will quickly accept it. In fact, they will find security in knowing that Mom and Dad are in love, while all of their friends parents are divorced.
The key to parenting, is being strict when they are young, and loosening the reigns when the child demonstrates responsibility. If you try the opposite, and try to crack down on a liberally parented child, you will only receive REBELLION.
You have to DATE your wife. The relationship and your love depends on it.
Once you're in your late 30s, your libido will slow down, and her's will speed up.
If she has a lot of women's issues, PUSH for a Hysterectomy. This will get rid of all the women's issues, and will DRAMATICALLY improve your sex life. Having a wife in her late 30s, or early 40s without girl parts is AWESOME.
Once menopause sets in, her libido will weaken, but by that time, so will yours, and you will have lived a happy life.
If you don't value her, or respect her. Then marriage isn't for you. Find a handful of slvts and fvck them as often as you'd like.
Hope you enjoyed my two cents.
