1. They Do Not Know What They’re Looking For. They’ll tell you that they know what they want and they’ll to convince you. They’ll do such a spectacular job at influencing your opinion that even you’ll begin to believe him. He’s certain of you because he chose you, but let’s be honest. He probably said the same thing about his girlfriend. The truth is, what he thinks he knows about his ideal girl and what he wants in a relationship amounts to the same level as what he thinks he knows his life is going to end up like – very little. Thus for as long as he’s trying to figure things out, he’s also going to keep his options open and well, you’re his option.
2. They Can Be Nice People. Because he’s a cheater, he’s automatically categorized as an asshole. However much we would like to tell ourselves that all assholes are bad people, sometimes that doesn’t hold true. Cheaters are humans and they too have feelings and a sense of being. Even though they’ve been unfaithful, it doesn’t mean that he doesn’t know how to treat a woman kindly. It’s true that he’s emotionally rotten, but who’s to say that he’s inept at treating a lady the way she wants to be treated? After all, that’s how he’s able to get his girlfriend and well, you.
3. Don’t Commit If You’re Not Ready. This is common sense and by far the main lesson to understand about a cheater. Infidels often become who they are because they say “I do” when they didn’t mean it and “I want to settle down” when really they don’t. While I personally can’t wrap my head around why anyone would say “yes” to doing something they don’t want to do (given that there’s no external pressure), I want you to vow to yourself to never commit until you’re ready. Love is fragile; don’t drag someone’s heart around if you have the intention to rip it apart in the end.
4. Being Emotionally Distant Has Real Repercussions. Cheaters are the ones who have personal issues that they have shame admitting to. This lack of emotional foundation combined with being unaware of what a healthy relationship is like has sent the infidel spiraling down a dark tunnel that he was never meant to enter. No one has shown him an example of a happy, thriving relationship and he doesn’t necessarily seek out a role model couple. He’s had to figure things out on his own and although he’s screwed up often, no one has ever called him out on his wrongdoings.
5. He’s Never Going to Choose The Sidechick. You held out hopes that he’ll eventually come to his senses and choose you in the end. You’ve shown him your love and affection, which at times has been reciprocated. As you stood in front of the mirror staring at your own reflection, you’re convinced that he’ll choose you. He said he loved you which a cheater shouldn’t do so you tell yourself that you’re halfway through that door. He said he didn’t love his girlfriend which was the reassurance you needed. It’s only a matter of time until he makes his decision, leaves his girlfriend, and BAM! He’s exclusively yours. That’s the ideal setting isn’t it? Yet after all these months of loving you and vice versa, he still remains with her. He’s long made his decision and unfortunately, he decided that you’re not for him.
But that’s okay.
The reality is you’re going through an unusual phase in your life and at some point, you’ll have to admit to your mistake. When you come to the conclusion that partaking in the scandalous game of infidelity is in fact wrong, perhaps that will be the day when you’ll be able to leave him. And when you do, you’ll realize just how much better off you are without him and how freeing it is to no longer hide a dark secret. 
