Disappointment
People set expectations of themselves and of others and when something happens and we fail to meet those expectations there is disappointment. Grabon certainly felt that way when he was expecting a strong mate that he could test his strength on and instead found a young frail mate in need of his protection.
Grabon also discovered that allowing someone else to feel the weight of your disappointment is damaging and painful. It was not something he had intended to do to his young mate, but she felt his disappointment keenly.
It is easy to overlook that disappointment is hard to swallow when it is aimed inwardly. As a weapon it can be a well honed one, but used carelessly and without thought it can be unintentionally sharp.
Makes you wonder how many relationships are destroyed this way. It starts as disappointment that simmers and blazes into resentment that neither one finds the source of and they part ways embittered and battered. Books get to end on a happy note which is probably why so many escape life in that manner.