The word "cheating" in a relationship simply means being unfaithful to one's spouse or partner. To cheat means to fool, to trick or to deceive someone. It's a very painful experience on the side of the victim (the one who's been cheated). From my own point of view, someone who loves you would never cheat on you; he/she would stick to you alone no matter what. True lovers would never opt for a threesome or a foursome. True lovers would not have the thought of sharing their love with anyone.
A female friend of mine told me she caught her fiance in the act of cheating. According to her, this said fiance is her first love and she has planned to be with her forever because they have been together for a long period of time. She has been faithful to him, but, she got cheating in return. She confronted her fiance and asked him why would he betray her love, but, he replied and said he can never date only one girl. He even told her to go and double-date, it's fine by him. She wept sore while explaining to me. I told her, from my own perspective, "anyone who truly loves you, would not give you a go ahead to date another person; he too would not think of dating another person." I told her plainly that she won't enjoy such a relationship; it would cause her nothing but continuous heartbreak.
Now, If You Find Out Your Fiancé is Cheating, This Is My Advice For You:
Go to God in prayer and fasting, because, the girl with whom your fiancé is cheating, might be using diabolical powers to trap him down. Ask for God's direction
Now, on the physical aspect, summon courage, sagaciously get your fiancé's phone, through text message, book a meeting with her (let it seem as if it's your fiancé texting her). If you succeed with the meeting, ask your fiancé in the presence of the girl he's cheating with, the following questions:
(a) why are you cheating on me?
(b) did she know we are dating?
(c) what is my fault?
(d) please, choose between me and her with the promise that you'd never cheat on anyone again.
Another option is, if you have caught him several times cheating with different girls, just walk out on the relationship, then pray to God to give you a good life partner who would love you completely without cheating.
Thanks for reading through, I hope these options help.
Please, readers, these are my opinions, and I stand to be corrected mildly.