In response to Liz's entry on mawwage, I thought I would write this. It might follow nicely from Question 1 as well.

People respect (or they say they respect) commitment in a relationship. If you say that someone may be less committed in relationship A (unmarried) than someone else in a different, married relationship B (a dangerous comparison to make, by the way), then it might be reasonable to think that you respect relationship A less. But from the point of view of someone in relationship A, depending on how secure they feel, your lack of respect is either of no consequence, or offensive.