Remember harrington, is she cheats on her husband with you, she will cheat on you with someone else.
Once a cheater, always a cheater.
Good point.
But really only important if Harry develops a desire that she and he be long term exclusive.
Trust me (based on my personal experience in the seven years between my two marriages) - he'll get tired of this gal within a few months at most, at which time he will be thankful when The Next Guy comes and takes her away.