Two people in a relationship, an exclusive relationship such as marriage or life-partnership, who love each other, which include having secrets between the two of them, things never shared with outsiders, are the ones allowed to have sexual intercourse freely. They also have this exclusive activity, namely sex that involves only them to only pleasure one another, which includes their most personal and private body parts, the genitals. Normal people keep this exclusive activity, a sacred activity for having the power to create life, private and call it having moral values. Not everyone wants to expose their genitals publicly or want to put their sexual acts on display, which is very good, since random sex and casual sex achieve just that—removing the sacredness of the act. Porn and other types of X-rated videos, pictures or shows have the tendency of smuggling with the brain and contaminate thought patterns.
Keeping sex with one's life-partner private, is the normal thing to do and it is also normal to be monogamous. Monogamy can also be defined as a sexual secret, besides sexual exclusivity; the secret between two people in a life-partnership. If these two people wanted others to know how they perform in bed, it wouldn't be a good idea to be in any type of relationship. Sex is a private matter, which comes after love was grown to completion—to full capacity.
This secret is violated when one of the two in the relationship, the relationship referring to nothing other than a contract, of exclusivity and keeping secrets, the contract referring to it being verbally or signed. During this type of relationship or partnership, if sex without consent is offered to a third party, it is a personal violation. This we call betrayal. Sexual betrayal is the worst form of betrayal, because it brings unfair competition into a relationship and causes totally unnatural feelings within the victim that sometimes last for years.
Anybody, who has ever been betrayed in a non-sexual way, knows how mortifying it is. Sexual betrayal is 100 times worse when a person is in a sexual relationship where you truly love the perpetrator.
Business-owners, who've taken apprentices and firms, made up of people, that took interns, taught them a great deal, even sometimes taken them from rags to riches, might deny this, but it is true that they are devastated when someone leaves, especially if they were poached by a third party, willing to be in breach of contract. And to top it, others say it's not personal. Crap! If an intern or apprentice was babied, it is very personal!! This is what being human is all about.
For all the above reasons, a person never ever cheats in any way if you want others to keep on loving you, respect you and even admire you. Nobody likes cheaters, as they are the world's traitors and if they can cheat sexually, you don't want them as business-partners or life-partners, because they cannot be trusted. The best way to erase love instantly, is by cheating!
