It is a very interesting concept especially if, as you point out Sotto, one person has erred significantly more than the other. I agree that even if one's "fault" is 10%, that is still his/her part for which forgiveness can be sought.
However, I think there are many ways of asking for forgiveness besides categorically verbally asking for it. For example, if a spouse strays outside the marriage and it is the other person who suggests couples counseling, that is a way, in my opinion of asking forgiveness. It is a way of saying none of us is perfect and I too could benefit from counseling.
When the one who erred 10% continues to want to work on the marriage that too is a subtle but genuine way of asking for forgiveness.
Me 41, H 47, M 15 yrs, S11, S13 BD 1: 11/4/14 we work on it; really I pretzel myself BD 2: 3/31/15 H goes down to "dorm room" 8/15: H back to MBR 10/15: H back in dorm room 1/18: H files, now divorced
