I see this all the time around here and let me tell you it is completely false!
Yes, there are those habitual offenders but you'd be surprised how many people actually don't repeatedly cheat.
If you smoke a cigarette once or twice does that mean that you'll always be a smoker? If you get mad and punch someone in the face once does that mean you'll always be violent? The answer is no.
Many people cheat because there is a disconnect with their spouse or even immaturity. Here's my story.
I married my 1st everything (besides kissing). I got married my senior year of high school and we already had a child together. After our 2nd I started to get more into a party stage because I panicked. I was so young. I had our last and dh was working over 3 hrs away. During the week he stayed with his parents cause they only lived 45 minutes away from his work so I was alone with 2 toddlers and a newborn. I was fine for awhile but I had severe depression and anxiety. Dh was never around and I started getting depressed and I resented him for everything. I began having an emotional affair with an ex and I told dh. I never went behind his back. It killed him. Then one weekend he was home and we got into a fight. I told him if he wanted our marriage to work he needed to quit his job or transfer closer or I wanted a divorce (I know now this was my immaturity. Dh works a lot now but I would never freak out on him over it. He works hard to take care of his family.) I got so angry I went to a party with dh and I got drunk and cheated on him. The next day I decided our marriage was over and I had plans to leave him for my ex. I came to my senses and cut all contact. Dh forgave me and we moved on... or so I thought. Dh slipped into a bad depression. He couldn't even be intimate with me anymore. A few months later he asked for a divorce. He told me that as much as he tried he just couldn't get over it. I convinced him to stay but a couple months later he ended up cheating on me with a now ex friend. It happened once and he felt awful. I know that if I hadn't have done the awful things I had done he would have never looked outside of the marriage for comfort.
It's been over a year since his affair and all contact has been cut with OW. We have worked so hard on our marriage. It took a lot but we're finally okay and in a better spot in our marriage than we have ever been. Cheating wasn't in either of our nature. In fact we despised cheaters. I know I could never betray him again. It took so much to realize what I have and how lucky I am. If I could I would take it all back because dh means the world to me.
I also no longer deal with the anxiety and depression, I no longer party or get drunk, and I am more mature. I think growing up has helped me see things clearly.
It's a case by case thing but not all people who have cheated cheat again so please be more open minded when giving advice to people about their cheating spouse.