Why do men and women always call each other by their first names when they have sex?

There is no clear answer to this question because it involves many different cultural, religious and historical backgrounds. Here are some possible reasons:

1. Excitement and nervousness: For some men, calling each other's names during sex can help them relieve tension and anxiety.

2. Enhance emotion: Some men may enhance emotional connection by calling each other's names, which can make each other feel more intimate and valued.

3. Express love: Some men may express their love and appreciation for each other by calling their names.

4. Explore and try new things: Some men may explore and try new things by calling each other's names, which will make them feel more exciting and interesting.

5. Cultural tradition: In some cultures, calling each other's names is regarded as a kind of respect and courtesy.

It should be noted that these are just some possible reasons. Everyone's situation is different and needs to be analyzed in detail.