2 children may be great friends and play well together, but when the 3rd child is introduced, it is not long before someone feels left out or left behind. I believe it is the same with adults- when a third person is added, someone is going to be slightly less than the others. Marriage is a commitment of explicit trust and that there is one other person that will stand with only you in difficulties and triumph. When David chose Jane because of a "scheduling" conflict, that trust was disolved (surely before that, but definitely there as a point of impact). So, no, I would not allow myself to be used or dismissed in such a way.