“yet strangely the iroquois-dutch relationship worked.” why does dennis come to this conclusion in spite of the numerous difficulties in the relationship?

Dennis found it hard to believe that they could work so well despite their cultural differences

Explanation:

Cultural differences often present a challenge in a relationship as it usually means that the compatibility between two people (in this case iroquois and dutch) is low. Religion, manners, values and perspective are complete opposites in this particular case however their relationship is able to blossom despite all of this factors hence why Dennis was surprised at the odds of the relationship working out.