Disclaimer: I do not own House, Wilson, anything related to them, and the wonderful episodes that were 'House's Head' and 'Wilson's Heart'.
There would always be a part of Wilson that could never forgive House. A part of him that would hold onto his anger, his bitterness at how unfair the world was. The part of him that would never forget the impact of what happened that night, even though everyone else had.
However, the part that greatly outshined his anger was the part that put House before his own needs; that was what everyone else saw. To everyone else it looked as though Wilson had completely forgiven House, or did not have an ounce of blame in him at all; but to Wilson it was merely an act of retribution.
House slept for three days after he first awoke from the coma, but the next time he woke up; he had no recollection of the bar, the accident, or the two days he ran himself ragged looking for Amber and the hint of hopefully saving her. It was Cuddy who filled in the gaps for him. She told him that he was in the hospital from a bus accident, that Amber was on the bus also, and that she had died. Strangely, House's mind did not string the course of events together.
Wilson managed to convince everyone that it was best that House did not remember the course of events that had landed him in the ICU most recently, and they were all relieved that House did not seem to notice that they were all hiding something from him. The rest of his recovery went miraculously well and he was discharged in a couple of days. Wilson decided to head House's home care more to keep up his charade than to truly help House, but he tried to convince himself that as long as both were accomplished then everything would be alright.
He ignored House's cold remarks and insensitive comments about his dead girlfriend as he fussed over his home recovery. Wilson knew, in the back of his mind, that House was trying to get him to leave; that House was showing him his unique brand of pity, but Wilson gladly accepted that over the look of deep guilt House had for him the first night he visited him in the ICU.
Time passed slowly, but profitably. House was soon back to work, everyone eventually learned to stop giving House looks of pity and Wilson their condolences, and everything began to seem normal again. However, Wilson learned that he could not escape his own anger or guilt. There were times when he coldly lashed out at House and there were times when he looked at House and could only see the pain in he had in his eyes prior to his seizure.
Wilson was glad that House could not remember anything from that moment in time. He was glad that House did not remember the horrible accident or how he pushed himself beyond his limits just for his best friend's fleeting happiness. Wilson did not want House to remember how he was ready to trade House's life for Amber's fading one.
He was also glad that House did not share any of the pain of losing Amber, because that was a pain Wilson thought that only he deserved.