Well it is, of course, but not only.
I got lost wandering around the internet for a while and found this:
Pay attention to whom you share your intimate energy with. Intimacy at this level intertwines your aural energy with the aural energy of the other person. These powerful connections, regardless of how insignificant you think they are, leave spiritual debris, particularly within people who do not practice any type of cleansing, physical, emotional or otherwise.
The more you interact intimately with someone, the deeper the connection and the more of their aura is intertwined with yours.
Imagine the confused aura of someone who sleeps with multiple people and carries around these multiple energies? What they may not realize is that others can feel that energy which can repel positive energy and attract negative energy into your life.
I always say, never sleep with someone you wouldn’t want to be.–Lisa Chase Patterson
This is sadly neglected in western culture. The Christian take is: the Act of Marriage (as it used to be called) is the marriage itself. The ceremony is for the family. The paperwork is for the government. The sex is the actual marriage of two people who engage in it. The bodies join the spirits together, and the souls feel it on a verrrrry deep level.
When you leave a sex partner in your wake, you are leaving a part of yourself you cannot retrieve. If you were having sex to fill the longing inside* then casual sex is a quick way to make yourself feel ever-worse. When you have one sex partner for life, that is the proper way.
*the longing is for a relationship with the Jesus, by the way. Believe it or not, it remains true that you need a relationship with God and the only way to have one is through the Jesus.