Given any choice, I would say none as well. It would seem that Itachi has seriously problems with relationships. At least with family anyway. He gets along with Kisame fine. But I'm not sure how Itachi would handle any sort of deeper relationship.
I say this based on how Itachi has been acting and assuming that his whole thinking that he is better than anyone else to the point of wrecking Sasuke for his own means. I do not think Itachi would ever be able to accept a person into his heart. Part of it is because I think he cracked under the pressure of being expected to be a genius. That was all he knew and so it seems like the only thing driving him forward. The reason for wanting Sasuke's eyes could be because Itachi actually fears someone surpassing him because Itachi has nothing else keeping him going. He has to be the best because he never knew of anything else. The focusing on perfecting himself in regards to that left little room for figuring out meaningful relationships.
But I suppose there is hope, there was Shisui...oh wait, he got killed by Itachi.
If I absolutely had to choose a character, I'd pick Oro--er, Kisame. They have that easiness between them as partners in Akatsuki. With how comfortable they seem with each other it seems like perhaps Itachi will see some positives in having a person around.
It would take awhile though. Trust for Itachi probably would not come easily, at all. Considering how one former member wanted his body and another obviously held anymosity towards him.
I can't really see Itachi in a relationship with anyone other than Kisame and even that with the boundries that it has now where they're strickly partners. Itachi just strikes me as too cold to really want or accept feelings other than his obsession with power and hate. Though I don't even think that he's capable of hate since its an emotion. Maybe he went through the Root traning like Sai....
He doesn't seem like the kind of character who would have any interests in anything but power and strength. Most likely, out of the given cast, I would say no one, not even among the guys. I'd vote for asexual.
But, then again, although it is pretty much highly improbable/impossible, I'm rather fond of Itachi/Sakura pairings just for the sheer sake of being cute.
I'm going to have to agree with those saying "none".
His overall mentality suggests he wouldn't do well in a relationships or even care about being in one for that matter. It's especially hard to pair him up with girls since the most interaction we've seen in that regard involved him kicking Kurenai into a river.
It's to the point, were I don't even think Itachi would care for sex. Rather he strikes me as the kind to be repulsed/terrified of intimate human contact. Or see it as very trivial, hence would never really think about it or pursue it.
I'd think his insanity and grander ambitions would override any desire of that kind. It's become clear that Itachi places power and bettering himself before everything.
The most realistic pairing to me is ItachixKisame since they obviously at least get along. Though still the chances of that getting to deep or working out in the end are very slim. Oh, and it's Shounen so they aren't gay