Sam should stay.

Because he’s still Sam

As is always the case with scandals of this sort, Sam Adams is still the man Portland elected. Whether or not a relationship he had in the past was a sexual one matters not one whit, so long as it was legal, which, by all accounts, it was.

Because he lied.

And we’re all disappointed. But the fact that he chose to lie says a great deal about his percipiency. He was quite right, after all, in his estimation that many people would not have believed him when he said that his relationship with Beau Breedlove was not sexual until after Breedlove reached the age of consent. Had Sam acknowledged the relationship during the election he would have been subject to the court of public opinion. Portland is progressive enough to elect an innovative and capable gay man to office, but that does not mean that blood in the water will not bring sharks.
Sam did exactly the right thing.

Because he told the truth.

Of his own volition Sam came forth with the truth. Fully cognizant, I hasten to add, of the shitstorm that would follow, as evidenced by time he chose to do so: amid the brouhaha of Obama’s election. Shrewd timing not withstanding, it shows that the truth is important to Sam, and that he understands that it is always better to come forth on your own that to be found out. Further, the official “investigation” that has begun will discover the truth, the empirical truth, and Sam will only have to content with what Portland thinks of what he did, not what Portland thinks he did.