I Fantasize About Someone Else... Is It Serious?

When the realms of possibilities give us permission to fantasize

According to a survey (carried out by sexyavenue.com) 37% of French people do it! And what does it matter, if you are still enjoying sex with your partner?
As long as it's a just a fantasy, nothing is wrong. Fantasy allows to maintain a balance within our psyche. Yet, it must not become obsessive if the balance of the relationship is to be maintained.

Fantasies fuel desire and intensify the pleasure that is the vector of fulfilling sexuality. It is an imaginary representation of conscious or subconscious desires. It can also be a good help for those who have a low sex drive.
It's up to you to know how to leave a barrier between the imaginary and the real!

Is fantasizing cheating?
Projecting an ideal of desire, such as with another man, can very often generate a feeling of infidelity. It doesn’t necessarily only concern sexual desire, it can also be about desire in the broader sense, where sexual desire is mixed with a sentimental projection and idealizes the other person. The fantasy then becomes an imaginary relationship that makes you really want it, because it is idealized.
Fantasizing about another person, does not mean infidelity, but it can highlight the fact that the relationship in which you feel safe is no longer sufficiently satisfying you from a sexual point of view. If you have doubts about sometimes fantasizing about another person, you don't have to feel guilty about your erotic projections.

When erotic projection represents a danger
However, if you regularly and intrinsically always fantasize about the same person, then your fantasy has become a sexual mechanism whose denial hides a very different problem. In this case, perhaps you should open up the dialogue with your partner, or with a professional.
Some women need to fantasize about another man. They say to themselves “I am safe, I am comfortable with my husband, but I am not having any kind of adventure”. They will therefore script a fantasy bordering on the forbidden. This fantasy allows them to experience something that they cannot otherwise have. By fantasizing about another person, they find a happy balance in their romantic relationship.
Jessica, 28, has always been able to tell the difference between fantasy and reality "I allow myself the right to dream about another guy, it makes me feel good. I know very well that these intimate journeys will not get in the way of my married life. There are my dreams and on the other side, the man I find in the evenings with whom I enjoy sexual relations, and with whom things are going well."
There are also those women who no longer enjoy their relationship, for them, fantasy can also seem to reveal a discomfort, or an unhappiness, it can even seem like infidelity.
Whether accessible or inaccessible, fantasies are good, of course, but it's all about dosage. 
And as Andy Warhol said:

Fantasy love is much better than reality love. Never doing it is very exciting.