“You must not have been meeting his needs.”
A version of this statement could also be said to men who discovered their cheating wives.
It is victim blaming, pure and simple.
The speaker often forgets that two people were not getting their “needs” met if one was not. Yet both did not respond the same way to those circumstances.
The other did not.
Unmet “needs” is such a cliche. It is a lame excuse for cheating–whether emotionally, physically, or both.
God does not say we can commit adultery if we have “unmet needs” from our marriage. It still is wrong. And the adulterous spouse is still fully responsible for choosing to commit adultery.