Seems obvious to me.

Since when have BB allowed two people in the diary room at the same time? According to the DS update they where in the diary room together... that in itself is weird, but the way they simply ignored Jade and went into the garden together... they are obviously trying to ensure they are the last guy and girl in the BB house at the end.

There have been several occasions when two or more HMs have been in the diary room together, so I don't think you should read much into it.

Plus, how can they ensure they are the last two in the house? There are no more nominations, the only way they could do this is by being liked by the public.

Since BB1 housemates have often gone into the diary room in pairs or groups, in fact it was on of the funniest scenes in BB1 with Mel and Anna trying desperately to flirt with BB to get more alcohol.

Kate and Jonny didn't ignore Jade, she was back in the bedroom and they decided that they didn't want to let it spoil their night, all play to them.

They can't do it with votes, true, but the way they are all pally, talking to each other about the entire experience, who they nominated, this, that, it just seems to me that they are intentionally excluding Jade, Alex and Tim from such discussions, to try and create a last two situation.

I may be reading too much into it, but I just get the feeling they are creating a situation simular to the end of BB 1.