Should she write a letter to the dude in army "by the way i'm dumping you, bye bye"?
Yes. If you want to explore while in an exclusive relationship, END said relationship if you are going to do so. Yes it would suck to be the guy receiving the letter, but it sucks FAR MORE to be the guy when he returns home, thinks everything is fine for a time, then learns someone who he should've been able to trust completely betrayed him
but fucked up societal norms (hello religion) push people into cheating secretly, for various reasons.
There are other situations. Simplest is: if you unsure about your partner and life choices and want validation. But it's socially condemnable to openly go exploring while marrired, or your partner won't ubderstand, which only leaves secretive cheating. Analogy: would you sell house each time you need to do some medical examination?
Admittedly I live in a place where divorce is fairly common, so this concept of societal norms compelling cheating is foreign to me. Also the "dating culture" where I am assumes that until people explicitly ask for exclusivity, no one should assume such, and both parties are likely to be going on dates with others to see who they pair with better. It is assumed that at the point of marriage, that both have agreed to exclusivity. The time to be unsure and explore was the months, to even years, before the ceremony, if you are unsure afterwards either stick in it and try to work on things, or end the relationship.
OK kids, looks like i have to explain further. When you are in marriage, you might be unsatisfied. Sexually, personal attention and other such things. Which in no way means that you don't care about partner anymore. You have no intention to abandon current relationships.
So it's okay for someone to want the benefits of the marriage and have a wholly dedicated partner but not uphold their end of the bargain? If someone actually CARES about their partner but doesn't feel like they fit in the committed relationship, they should be up front and end the relationship or try to work on things. Cheating is a wholly selfish move that someone who only cares about their own feelings and benefits they get from a relationship does. Someone secretly cheats when they want the benefits of a wholly dedicated partner, but is unwilling to provide the same. I can not see how it can be framed as they truly care for their partner if they commit such an act.
Edit: Again I am admittedly coming at this from my own cultural situation where cheating is seen as utterly abhorrent and a complete betrayal, and people divorce over shit like not wanting to paint the walls of their home the same color (likely had plenty of other issues, but I shit you not that WAS the breaking argument for a prior couple I knew).
but eh.
