Most of us fail our way to success when it comes to relationships. If this were not true we'd all be married to our high school sweethearts!
Rarely does someone win the "relationship lottery" the first time they "fall in love". Some people never ever love as deeply again even though they force themselves to move on. The only reason why they're with a new person is because their ex no longer wants to be with them. In many ways it's like marrying a widower or widow. They're with us because they can't be with them.
Having said that it does not mean they do not love their current mate or spouse. Their current partner is simply not "the love of their life". In reality they're actually in love with a "period of time" and a romanticized notion of what might have been or could have been. They fail to understand that in order for her or him to be "the one" their ex would have to see them as being "the one". If someone dumps you it's because they didn't believe you were their "soul-mate".
Awhile back author Lori Gottlieb wrote a book titled "Marry Him: The Case for Settling for Mr. Good Enough". Essentially she was encouraging (women) to let go of finding their "fairytale Prince Charming" or "the man of their dreams" and instead become more "practical" instead of watching the years roll by alone.
The book was both praised and attacked. Not many people welcome someone telling them to "let go" of a dream. However truth be told "settling" really means we took what we consider to be the (best) available option left to us based upon the effort we were willing to exert. Nevertheless "settling" is still a (choice). If we could have done better we would have done better!
In other words if someone marries you it is because they believed (you) were their BEST option. Awhile back I wrote a hub on this. http://hubpages.com/relationships/Relationships-Do...
There are basically two ways to react to this assuming one's spouse is loving and loyal.
1. You can feel sorry for yourself because you are not "the love of their life".
2. Be grateful it didn't work out for them which allowed you to find the love of (your) life!
There are only two ways to experience joy and peace of mind in relationships: we either get what we want or we learn to be happy with what we have.