Because the writers are REALLY, REALLY desperate to find a reason to get SE together again & they are so out of ideas they'll go with the most ridiculous idea... But seriously I can't think of any logical explanation except of writers desperation. Seriously. I doesn't even make much sense.
Well, according to the episode, every 'Silas' DG ends up with the matching 'Patrova' DG. So Silas is with Amara, Silas's اگلے DG is with Amara's اگلے one, and so on... This is supposed to be the reason. But I agree, this whole SL is just stupid. And honestly, if I was a SE پرستار I would've been even مزید mad than I am right now (as a DE fan).
If The Vampire Diaries‘ Silas and Amara were destined to be together and Stefan and Elena were each other’s true love, who is Katherine’s soulmate? There seems to be a Paul Wesley-portrayed character missing. یا am I totally misguided? –Bonnie Vlada Gelman delivered your Q to Julie Plec during her visit to the set in Atlanta, and the TVD boss came back at آپ with… مزید questions. “You have to ask yourself: Was it Katherine and Stefan that perhaps were fated and there’s another doppelganger yet to come? آپ never know,” Plec hedged. “The key thing is that’s what the universe supposedly says. Is the universe real? Is the universe right? یا is it just one big prophecy and it got bastardized over the years? That’s going to be part of the fun of seeing how their relationships all اقدام forward.” link
Stephan and Katherine were "fated" to be together. Not Stephan and Elena, though they do have a deep love. The whole DG symmetry (Silas/Amara -- Stephan/Katherine -- ?) got thrown off when they started becoming vampires. It all would've been different if they didn't live forever, hence there being مزید than one Amara DG existing at the same time in the first place.
Also, if آپ think about it, Katherine really never fell out of love with Stephan.. and if she wasn't such a bitch, he probably would've never fell out of love with her (regardless of the Damon situation). Think about it, its the whole reason he was drawn to Elena in the first place..