According to the Wife of Bath, what complaints do men have about their wives?
To find the answer to this, I think that you need to look in the Prologue to the Wife of Bath's tale. In the prologue, she talks about things that her husband would say about wives. The basic idea was that wives were faithless and treacherous and were too quick to hurt men if they possibly could.
For example, her husband talked about various women who had killed their husbands. He even mentioned ones who would sleep with another man while their husband's corpse lay there on the floor. He seemed to think that this was the sort of faithless behavior women would engage in. Here's a quote about that:
Of wives of later date he also read,
How some had slain their husbands in their bed
And let their lovers shag them all the night
While corpses lay upon the floor upright.
And some had driven nails into the brain(60)
While husbands slept and in such wise were slain.
And some had given them poison in their drink.
In addition to this, her husband also talked about women as being terrible nags who would make their husbands' lives a living hell. He talked about them being contrary and always wanting to fight with their husbands without any good reason for doing so. Here's a quote about that:
Better,’ he said, ‘your habitation be
With lion wild or dragon foul,’ said he,
‘Than with a woman who will nag and chide.’
‘Better,’ he said, ‘on the housetop abide
Than with a brawling wife down in the house;(70)
Such are so wicked and contrarious
They hate the thing their husband loves, for aye.’