4. They idolise a cheating lifestyle
They are greatly influenced by characters who cheat and tend to like them. They live like them because they relate to them.
5. They are insecure
Many cheaters become who they are because of their bitter past which have left them with lifelong emotional scars. They feel that they do not deserve their partner and so the insecurity arises. They begin to fall for the opinions of those outside of their relationship and to cater their loneliness, they cheat.
6. They forget things
They tend to forget your birthdays and over a period of time your tastes too. They forget things they promised to you like taking you out on a date on Friday night.