Here's the corrected version:
"An adulterer bitterly resents his or her situation in marriage."
Explanation of the changes:
Verb Tense: "Resent" should be changed to "resents" to agree with the singular subject "an adulterer."
Clarity: I added the word "situation" to clarify what exactly the adulterer resents. Without this word, the sentence might be vague, and the meaning could be misinterpreted.
Overall Structure: The corrected sentence now has a clear subject ("An adulterer"), verb ("resents"), and object ("his or her situation in marriage"), forming a complete thought.
By making these changes, the sentence becomes grammatically correct and conveys a clear meaning.