Lies, infidelity, and half-truths... Not much difference, except adultery takes it way beyond what I would personally be willing to reconcile. My wife (hypothetically - I am not married, but am divorced) is my best friend. A person I can trust with my life and, more importantly, the lives of my children. If a little dick during a separation is worth ruining that, I need to find a better woman.
Yes, I am capable of forgiving her, but forgiveness is dependent on repentance. Lying or hiding facts about what transpired is NOT repenting, it is denying. They want forgiveness, they earn it. No one is obligated to forgive unless true repentance is exhibited, and forgiveness does not equate to absolution. Like another poster stated, just because I have forgiven your wrong against me and the covenent we shared does not mean I will accept it or forget it - and certainly does not obligate me to trust you ever again.
The very moment an act of such a nature occurs, the trust has ended. Which means the marriage has ended. I teach my kids that sneaking and lying and deceit is wrong. Why would I permit it from my wife, presumably their mother?
Every time I reached to hold her, I would be reminded she wanted another man simply because she figured a separation gave her some magical permission to get a little sex on the side.
Seems to me that if she cared about the marriage she would have been working to reconcile, not working on getting laid. Given what her priorities were at the time, I'd be a fool to see anything but a divorce pending, and would wish her the best in her future decisions. But no way in God's Earth does she get to share my home, my possessions, or my affections ever again.