So many reasons I don't understand/like this couple and I've written a lot about this in other places, but never here, so...yeah :)

In 1864, Stefan didn't really know who Katherine was. He didn't know she was a killer, that she manipulated he and his brother, whether it was in the purpose of taking away a person's judgment o just having her cake and eating it too. If he didn't know about Katherine's flaws, how could he be in amor with her? How could he know she was an angel, o anything, for that matter, when he was shielded from it all?

I know people have dicho that the reason Katherine was in amor with Stefan was that she was an “angel” as a human and he saw that in her, but I have to point out exactly who she is behind closed doors. No one is perfect – and I've met some pretty angelic people – and I don't hold Katherine to the standards that many hold Elena to. That said, Katherine is not an ángel por any sense of the word. She has flaws (and I think they're damn brilliant, honestly) and those flaws are apart of who she is now. Why in the world would tu want a relationship with someone that will never amor tu for who tu are?

The statement that Katherine has come back for Stefan has barely been acknowledged at all. Katherine says she loves him, but when she has the house alone with Stefan and Damon, tu can see from 2x16 that Stefan is the last thing on her mind – even though he is in the house and unoccupied. She claims she's come back for him, but her “seduction” of him? She breaks SE up once and, after that, the mostrar never demonstrates Katherine trying again, o even trying to persuade Stefan to doubt Elena/seduce him. The two episodes that have Stefan/Katherine motivations are Memory Lane and por The Light of the Moon and, as far as seduction goes, are basically limited to dreams.

Not to mention, after so many years of knowing Stefan was alive and never contacting him o letting him know, Katherine came back, first and foremost, for Klaus' little sacrifice. Just saying.

And, finally, if Ripper!Stefan is going to be a huge part of the siguiente season (fingers crossed) then I really don't get how these two make sense; it's like Katherine's comentario about how Stefan plays rougher (and she seems to like this fact) but her being "touched" por his gentleness and sweetness. Either she loves Stefan for who he is - not the fact that he's turned off his emotions/humanity, for example – o for the ripper she wants him to be. She can't expect both, especially if she puts más effort into seducing Stefan at his worst than she did when he was at his best.

THIS. SHIP. MAKES. NO. SENSE.