In my opinion, this issue is something each couple has to work out for themselves in regard to consideration of feelings and showing mutual respect. Ball park observations and knee jerk reactions are totally useless because the situation of each couple is different and unique. We are the experts when it comes to knowing our SO's and are the best ones to make the call. If it is an issue, discussing things rationally and intelligently is the best way to go. This is true teamwork in action.
Past disappointments (on both sides) are just that--in the past and we should consider them as a learning experience and move in a positive direction. If we truely want the relationship to be successful, we will have consideration for one another's feelings to the extent possible.