4 year relationships

I've been searching for my life partner--someone who will be "Mr. Right" forever. Is this just an illusion? Many people only stay together for life because they have children or financial ties and not because they are happily in love.
This isn't encouraging.

"Four years after getting married, about 10% are as happy as when they first got married--90% are not. Twenty to thirty years later it continues to go down." -- This Emotional Life, part 1.

My longest relationship was four years and my average is three.

If I change my outlook on relationships to just sharing a wonderful few years with someone before moving on, would that be so bad? Could it be healthier?

Tolerance would be lower, enjoyment higher. Expectations would change.
Accepting that relationships are meant to be temporary creates happier times together and less stress. No more sticking it out super-gluing a failing relationship. No disrespect. Relationships would be complimentary. People wouldn't allow themselves or their partner to fall apart. No compromising of yourself for your partner. When the relationship is no longer synergistic, breaking up would be logical and wouldn't cause hard feelings. Both people move on in whatever way that continues making them happy and remain friends.

With this adapted foundation, flourishing relationships may even have long term possibilities. Hmmmm, I will have to give this some more serious thought.