Washington, December 20 (ANI): A woman's relationship satisfaction changes as she nears ovulation, but whether or not she's more or less happy with her guy depends on his sex appeal, researchers say.

In a new study, heterosexual women who rated their guys as highly sexually desirable felt closer to their partners and more satisfied with their relationships just before ovulation, as compared to their less-fertile days.

The opposite was true for women who said their partners were less sexy; they felt less close to their male partners and were more critical of their mate's faults as they approached ovulation.

Previous research has shown that the type of man a woman prefers tends to change across her ovulatory cycle, as she becomes more attracted to masculine faces and bodies, and bilateral symmetry, when she's fertile.

Another recent study showed that heterosexual women actually look and sound more attractive to guys on the women's fertile compared with non-fertile days.

"This is the first research to show that these changes have implications for relationship functioning," Fox News quoted study researcher Christina Larson from the University of California, Los Angeles, as saying.

Hormones likely influence these fluctuating preferences and evaluations. However, the researchers didn't directly measure hormones.

"So we can't say exactly which hormones were responsible or how exactly they change women's behaviours," Larson said.

Estrogen, which peaks at ovulation, is a strong candidate, she said.

The study involved 108 heterosexual women who had not used birth control in the past three months and who were not pregnant or breast-feeding.

The women, who had been in committed relationships for an average of two years, answered the same questions during two sessions, one during their high-fertility phase and one during their low-fertility phase.

The subjects self-reported where they were in their cycles, and the researchers confirmed the high-fertility session with an ovulation test.

The questionnaires included prompts like "How desirable do you think women find your partner as a short-term mate or casual sex partner, compared to most men?" and, "How sexy would women say your partner is, compared to most men?" The women also answered questions about their closeness to their partners, their partners' faults and virtues, and the women's commitment to and satisfaction with their relationships.

The good news for men is that although a woman's time of the month seemed to influence her feelings about her partner and relationship satisfaction, her commitment to the relationship stayed constant throughout the cycle.

The study has been published online in the journal Hormones and Behaviour. (ANI)