Sex and relationship expert, Dr. Trina Read, is ready to answer your questions.

Sometimes I just feel more sexy than other times. Is there a reason for this?

The next time you’re feeling "more sexy" take a look at your calendar and ask yourself whether you’re ovulating. Evolutionary psychologist would say you have reached peak fertility.

While ovulating, the female brain kicks into competition mode and is subconsciously driven to attract the best quality sexual partners.

And if you think you have an unchanging "type-of-man," think again. Women prefer quite different kinds of men depending on whether they are fertile. For example:

1. When women are at peak fertility they want the highest-quality genetic material for their children and will prefer masculine men—high genetic quality is indicated by level of testosterone.

2. During the rest of her cycle a woman wants to secure the most generous and stable source of goods for herself and her children. Now the nice-guy provider looks appealing.

Research indicates women take more care with their appearance and choose more revealing clothes to wear. The University of Vienna digitally analyzed pictures of 351 women going out to Austrian nightclubs and collected a saliva sample from each. Women whose clothes were tight or showed a lot of skin had higher levels of estradiol, a female hormone that is elevated around the time of peak fertility.

Interesting Tidbit: Women in the fertile phase show more interest in erotic materials and will select movies with more romantic or sexual themes.

My partner doesn’t like me being friends with my guy pals. It seems unfair since I’ve had these friends for years.

Not to say I agree with your partner, however, let’s take a look at this from his perspective.

In a recent study on whether men and women can just be friends, researchers found men were more likely to report being attracted to their female friend and more likely to report their female friend being attracted to them. This was true even though they knew they were more attracted to their female friends than their female friends were to them.

Women on the other hand, underestimated the level of attraction their male friends had for them.

This study also showed that it didn’t matter to the men if they were in a relationship or were single. Women made a distinction: single women reported more attraction for their male companions.

I do believe men and women can be friends. And early in the relationship is the perfect time to set the boundaries for how the rest of your married life will be.

If you are certain that your male friends are on the same wave-length and won’t cross the relationship-line, then your partner needs to accept your friendships.

Interesting Tidbit: In our past, male-female friendships provided us with additional mating opportunities as anyone you hung around with was likely genetically related to you.

Dr. Trina Read is a leading relationship and sexual health expert and educator; and is a best selling author, media expert, syndicated blogger, international speaker, magazine columnist, and spokeswoman. You can find more information at TrinaRead.com and follow her on Twitter and Facebook.