I trust your competence.
Sometimes, what's left over after decay warrants keeping.
Or even better, sometimes the fluctuation in SMV levels plays a significant role.
Let’s take an example: imagine that, by the fifth year of the relationship, the man has let himself go, he’s gained weight and become less attractive. As a result, the woman loses interest and starts looking elsewhere.
But then, the man suddenly begins to take care of himself, improves his appearance, and raises his SMV. At that point, the woman becomes attracted to him again.
In this case, there was a natural decline in attraction, followed by renewed commitment and personal growth.
So the relationship that ends in the fifth year, at this point is "delayed" by this event.
There’s also another perspective.
You mentioned the 5y mark, and that can be true for many typical relationships. However, there are couples who share much more and are bonded by deeper social and structural ties.
For example, couples whose families are closely connected and present, with active grandparents and great-grandparents, whose parents are still together, who work together (own their business), or have the same professional background.
Add to that children, shared life projects, planned vacations, a similar lifestyle, also the social perception of them as a solid, established couple (the name the LTR gets in the mouth of others, like "Oh John and Jane of the third street, etc etc").
As you can see, there are many factors that contribute to the strength of a relationship, far beyond the initial feeling of love that may fade after 5 years. In these situations, people have a lot more at stake, and many more reasons to stay together or to work on the relationship, or just to say "The pros outwork the cons", so they don't make a move.
What do you think about this perspective? I’m really curious to hear your thoughts.