Love is not an emotion.
Infatuation is an emotion.
Infatuation is the commonest means through which love arrives.
If love were an emotion; that is to say that if love is a particular emotional state, then it is conditional.
For the emotional state to occur certain conditions need to be met.
This means that the other has to behave in a certain way in order to produce this emotional state.
The other cannot be themselves; they must wear a mask to maintain the emotional state in the one they want.
It is because people have confused love with infatuation that controlling and abusive relationships occur.
So what is love?
Love is acceptance.
After a while infatuation will diminish; or it may be like a sine-wave. Sometimes strong, sometimes weak.
Once this occurs there are 4 paths open to the couple:
They will each attempt to force the other into replicating the behaviour that produced the emotional state of infatuation.
They will believe they love the other; often believing love to be some form of possession, and will try to keep them as a possession.
They will part ways and seek infatuation in others; going from partner to partner until they die or realize path 4.
They come out of infatuation and notice things about the other that bug them; but they realize that nobody is perfect. So they accept the imperfections.
Love is acceptance of the whole person; warts and all. I believe eventually they will come to adore the imperfections of the other if the other is one of their ones.
Love is a choice.
Of course sometimes the imperfections of the other can be too unbearable; to accept their imperfections you would have to part with something vital to yourself.
This just means they are not one of your ones.