You're like my ex...
God, I hope I don't get unlucky and end up with another person like you and her. You've cheated before and now you cheated again. You'll find yourself never satisfied in a relationship. You'll end up feeling like the relationship isn't as exciting as it used to be, which is normal. But, since you've already cheated a few times, you won't see it as a big deal since you've already done it. May I ask you how many times you have cheated? Did you feel bad about it those times? If not, I honestly think you need to get some professional help before it gets out of control and becomes a problem when you do, if you ever do, get married.
Cheating should be illegal. I look at it as causing harm to another person, almost like abuse or harassment. I know in a few states it's illegal to interfere in another persons marriage. I think it's good idea actually. Marriage is like a legal contract, and interfering with something like that should be illegal.