It is not birds, it is mammalian predators that follow scents, and if you approach a nest too often, or too closely, you may well be leading a predator to the site. The next time you visit, the nest will be abandoned. The birds smelled you and ran. There are very good reasons for staying away from bird nests. Birds may find your intrusiveness offensive for many reasons, but one of them is not the way you smell.
Some birds mate for life.
So, well, human. The idea appeals to our sensibilities and our morality. The problem is that it has virtually nothing to do with humans or birds. Mating for life is an ornithological shorthand that stands in contrast to those birds that change partners every year, or even several times in the same year. It does not necessarily mean what we think it does, however.