Seven years is a long time, and that's why she's still sniping at you about it. She's given you all this time, and time is of the essence for women because unfortunately, our potential to have viable offspring has a limited window; therefore, you do something like cheat on her after she's invested all that time on you, and it's a huge violation of everything.
The perception of time is different for women than how it is for men, and it's ramped up immensely when you have societal pressure telling you that if you don't have a husband and kids by X age then you lost.
She's given you seven years and you go cheat on her, she may have the fear that seven years has been wasted, however, because she took you back, she considered that amount of time and doesn't want to throw away that investment, therefore, you have to show her that her investment is still valuable. Women cannot stand their time being wasted- some have more patience than others, but as a man, the best thing you can do is to never waste a woman's time, because time is one of the most valuable currencies she has.
