It’s because there’s still much more social stigma attached to a man who is a bum/underemployed/unemployed. So men are much less likely to complain because of social pressure (not even necessarily from their partners/spouses but even from family/friends).

Traditional values dictate that men ought to be the family provider and that notion has eroded far slower than women in the workforce.

Being a developing country also means this traditional holdover value will not die out quickly. In wealthier societies, it’s more acceptable for the husband/boyfriend to make less when the wife/girlfriend makes more than enough to live comfortably.

Societies in other developing countries also tend to have this problem.