Might seem petty and immature to you, but the damage an abusive parent can do to one's psyche is real and carries on to this day. Hatred and revenge are poison and don't have to make sense to people on the outside looking in. I think some of this criticism is harsh and does not consider the the values and mores of the time, the whole institution of nobility and honor codes, gender roles for the period, or taking vows seriously. As a former romance novel reader (ions ago) I see Simon's obstinance for what it is, and never had any doubt that his feelings for Daphne would win the day.