The statistic that floats around the internet is that marrying your high school sweetheart occurs less than 2% of the time. I have attempted to find an actual source but was unable to come up with one
(CBS stated that among women they polled, 25% stated they married their first love). Again polling is difficult as "love" is often defined in hind-sight rather than in the moment. But the statistics show that among married women, "first love" does not necessarily lead to marriage. So I believe that I'm being realistic according to statistics.
On a logical level, real things happen to people outside of high school. While in school you are extremely naive to meeting expectations of the work force, making sure to meet deadlines, and managing different aspects of your life. Giving up time for a solid relationship costs you hours and possible job promotions because you decided to put those hours into taking care of your child. There is no more mommy and daddy who you can cry and turn to as your safety blanket when you can't meet expectations lined out for you from a Fortune 500 company. And these pressures eventually creep into the relationship, into your beloved spouse, and even into your own child.
The term "happily married" I feel is happily misconceived. There are new responsibilities when anyone has a relationship. The fact that you have a partner who you want to impress and work hard for is a joy at first. As you get older, she may not seem as attractive or entertaining. But you made a pact and an obligation that you would be there for here, in life and death. If your partner isn't reliable and you feel that he/she doesn't put as much into the relationship as you do in order to make it work, these things can wear you down and make you question why you decided to dedicate a very large portion of your life for this significant other.
Only time can attest for whether or not infatuation is really love. And even then, time is not the accurate term, but rather growth. There are plenty of adults in the workforce who are still as immature and irresponsible as they were in high school. If you want me to get "real", then I suggest you explain to me how I should get "real." As in my mind, I'm the only person who attempts to rationally find a reason for my opinions rather than simply accepting my opinions as fact.
I was partially joking in offering blatantly pessimistic definitions that contain a grain of truth. Responsibility is all about being accountable for yourself. But this also means being responsible and looking out for your co-workers and class-mates. This is especially true in the workforce.
In Organic Chemistry, it would take one person 10 hours to synthesize all the intermediate enzymes and carbon compounds required to run the whole reaction. The work was split up where each one of us was responsible for designing a specific step to that we could see the reaction run to completion. One guy who was pre-med, was seriously screwing up because he couldn't pipette correctly and do basic dosage calculations. Basically if the end-product failed, we all failed. So we assumed responsibility and took turns tutoring him in order to make sure that he finally got his part of the experiment done correctly. It was a pain in the butt. But that was the responsible method of action.
In regards to the topic at hand, marriages are built on trust and responsibility. If your wife finds a more attractive partner, who makes her life wonderful in all the ways that you couldn't, then she shouldn't abandon you simply because she found a better mate. She made a promise that she would be yours for life and for death. She loves you, therefore she will stick with you. Even if there are better fish in the sea who are vying for her love and attention.
Compound this circumstances with your partner possibly losing their job, especially in light of the recent recession, makes things difficult. In The Office, David Wallace loses his job as a corporate CEO and is having a blast doing nothing and swimming around in existentialistic pointlessness. If you watch the reactions of his wife, she doesn't know who he is anymore. He's changed completely from being this critically goal oriented man, to being a childish optimist. When Michael Scott drives to his home in order to get advice from his former CEO, he is aghast to find this "weird creature" that is "living in David Wallace's house."
In a sense, your job becomes your life that you dedicate to your significant other. If you are so used to telling your loved one that you are working for the kids, the family, and the relationship; what happens when you no longer have a job to work for. The irony is that you love someone, therefore you want to spend time with them. But when you begin to live together, you discover that you have responsibilities. And that in order to fulfill these responsibilities and live together, you need to separate from each other in order to earn the wages just to make a home for both of you to return to at the end of the day. Adding a kid into the mix means having less time for you to love each other. At times like these, it's easy to drift apart and for complications to occur. The most important indicator to show that you really love each other is to stick with the relationship when things get tough. To me that's more an indicator of love than flaking out in the relationship to find someone better.
I have my own reasons for feeling very strongly on this issue. My opinions are unfortunately not just theory craft. My mother came to me on numerous occasions, scared that the relationship with my dad wasn't working out. I didn't always encourage her to be submissive and to stick with the relationship. I had to dig under and find out the real issues and always offered her numerous choices. At times I comforted her, assuring her that everything would be alright. Other times I have told her that she was being unrealistic and should realize her fears were over-exaggerated. I believe my parents love each other, but they could have found better partners to match with instead of having an arranged marriage.