Each has been studied.

Each tends to be brought up by one gender when trying to demonstrate the other gender "doesn't love"

Well the two facts paired together

(1) wives leave their husbands because of husbands' job loss

And

(2) Husbands leave their wives because of wives' illness

Indicate that the transactionality is mutual. Either both prove that relationships are transactional, or neither do

As SMBC put it:

Sex!

Money!

We decided to keep our wedding vows succinct

Relatedly, some people seem to think that the transactional nature of relationships is both true and should be ignored. Seems like a great way to be exploited.

So which is it

(1) Men love women, and women love men, despite these facts

OR

(2) as proven by these facts, love does not exist: women don't love men, men don't love women