Fair enough. I see your distinction, though the strictly positive definition would probably never be pointed out as off-putting.
Well, it's not much of a stretch to interpret the wording "through eternity" as "without regard for time passing" (rather than "until the end of time"), especially if they're assumed to have already been waiting for Twilight for what might've been hundreds of years.
I imagine the two unicorns having had much to talk about over the decades.