I shall now continue my discussion of yandere and their desirable traits.
LOYAL: She will never --- NEVER --- betray you. Even when you're dead.
LOVING: She knows the meaning of true love like no other girl, or even you, will ever know. Some of the love is for your own good.
CARING: She takes her entire budget of caring and places it all on you. Other people are... irrelevant.
PROTECTIVE: No bad fortune, villian, or evil conniving cheap slut will be allowed to have their ways with you for long.
HATRED: For other girls as pure as the darkness between the stars.
DETERMINED: She will never --- NEVER --- give up. Even if you end up hating her for it. She’ll never let you down, either.
OBSESSIVE: There is pretty much no limit to how far she'll go just to get your attention. Once you go yandere, you can’t go back.
BRUTAL: Why should she go easy on those who threaten to steal you away from her?
PROACTIVE: Friends? Family? Better get rid of them before they start taking up precious time you could be spending with her.
DETESTING: Everyone that isn't you.
One of the few potential cons that I can see is that intellectual conversations are nearly impossible with your yandere. She can't comprehend anything outside of the context of your relationship with her. War in Iraq? You are saying you think she's too clingy and so therefore some cheap slut is poisoning your mind against her. The nature of the universe? You are trying to break up with her so therefore some cheap slut is poisoning your mind against her. It's okay to participate in activities that don't involve her, by all means, please do, but it's very, very difficult to get your yandere involved in anything that doesn't directly have to do with her loving you. It's not impossible, but I prefer to keep mine in the kitchen baking or knitting and would rather not provoke her.
Speaking of my own personal methods for dealing with yandere that might not work for some people, when a girl I’ll accept becomes yandere for me, I become yandere for her. That's right, all that crazy shit. No looking at other men, not allowed to leave my presence for more than 3 hours, etc. I’ll stalk my precious yandere all the time and make sure no other men can get near her. Well, at least at first.
The problem with continuing this practice is that you can't out yan the yandere. It would only drive her to a higher state of mental instability. Think about it - you're stalking her everyday. She realizes it's YOU who's the third person walking by her to the grocer's, or getting her car fixed, or chatting with the neighbors as people jog by. She starts wondering, "does he think me unfaithful? But... but that's impossible. It's just him I care for - only him!"
Then the attempts to reassure herself begin. More painful, scarring sex play, just to let you know "this body is only for you." No matter how violent or messy, she does it with a broken smile. The meals become dull as she starts going out less and ordering in more. Minor things she can pick up from faceless stores to show you that she doesn't NEED other people, so long as she has you. The artwork of herself she leaves in your desk at work (should you bother to show, as you're so busy being full of her and dumping bodies of the ones who'd dare even glance...). The jagged crying night sessions - tears spilling down her face as she smiles delightfully, her voice full of laughter as she takes on any abuse, just for you.
The moment of broken screaming when she realizes despite all this devotion, you STILL don't trust her.
And then you walk in one day and find that she's jammed the biggest kitchen knife she could find into her sexual organs. That tearful, joy-filled face saying, “you know, darling, you were right, my thoughts were impure and clouded by other faces, so I punished myself, but now it's fine. I’ve punished those involved, too, those evil people that caught me in my moment of weakness…”
The police will be over in the evening to arrest you both on the collection of bodies in the basement unless you had already prepared an escape route for different but similar reasons. So yeah, you need a cut-off point for being yandere to your yandere.
DOUBLE YANDERE LOVE IS THE TRUEST LOVE.
On to another point. I think that sometimes the attraction to yandere is based on the childish, idealized belief that your love can cure her. PFFT. This is DANGEROUSLY NAIVE. "Cure" her? Why would you want that? Her being an obsessive, potentially-dangerous psychotic is the whole POINT. To say someone finds such a person attractive out of some misguided belief they can "fix" them is like saying a "chubby chaser" finds big women attractive out of some belief that he can get them in shape, when really he just really likes the fatties. In all likelihood the stress of a relationship would make her psychosis even worse.