I hope this is a joke. Physicists coming in and claiming things are critical here and there is a common thing in neuroscience, and it's in fact a rather serious and interesting field, but this has not prevented it from attracting some kind of jokes on the approach physicists have to neuroscience.

This paper however is way beyond that, it has lots of problems:

It claims it wants to investigate phase transition in the neuroscience of the brain, but only does so through the mediation of the phenomenology of love. And the latter is also only examined indirectly through literature. And literature is mediated through the lens of a few readers.

Then, this is based on what, 2-3 books? And on a few readers? The chances of cherry-picking are huge. Plus, the experimenters themselves chose the sentences to be examined, which introduces a massive bias. They claim the "time" between one and the next is constant.

In conclusion, I hope this is not meant seriously, but the fact that they acknowledge grants gives me little hope.