Right, you do this small act of service because you are in love with your partner. Ideally not even because it makes her happy, but because it makes you happy to make her happy.

The upshot of the article, IMO, is that they were no longer in love.

And that lack of love became most apparent by observing all the tiny acts of service that people in love do for each other, and people who are merely co-habitating and perhaps also co-parenting, do not give a flying fuck about and use as a safe thing to argue about instead of admitting the truth.