Not necessarily, I was a serial cheater for the first seven years of my first long term relationship, we stayed together 14 years and I was faithful for the last seven, then she left me for a friend... go figure!
My next long term relationship lasted seven years and I was a cheater again, but not once I had gotten over the first dumping.
We had a son and she went off sex 100%... she recommended a mistress (common in Spain) and I found one who I was with for another seven years. Oddly I was not a cheater with the mistress, but then she was a hot mistress and I had no need!
I broke it off with the mistress when I met my now wife, and we have been married 12 years and we are 100% faithful and monogamous, but then we are both Christians (now) so we would /should be!
If a man loves a woman, and shows it, if a woman respects her man, and shows it, the chances are neither will stray.