Women who settle down with a stable guy instead of a sexy one might subconsciously struggle with that decision during their most fertile window of the month, a new study suggests.

Just before ovulating, women with a more reliable long-term partner are more likely to have negative feelings about their beau than those paired with more sexually desirable men, the researchers found.

"A woman evaluates her relationship differently at different times in her cycle, and her evaluation seems to be colored by how sexually attractive she perceives her partner to be," researcher Martie Haselton, a professor of psychology and communication studies at UCLA, said in a statement.