Billy was NEVER interested in Aleisha sweety, in fact I thought the whole charade was fake all along, you must of missed when he was constantly pushing her away and generally not being very affectionate at all, I saw it several times on the live streams back in June/July, in fact had it not being for Kyle Sandilands opening up his big mouth to them about what the publics perception was of their relationship (or his perception), I can tell you that Billy wouldn't of taken it further.
However I know what an opportunist Billy is and I think it's obvious why he decided to end up with her, come on don't kid yourself, there is money involved and there is quite a lot of it, Billy is smart ending up with her because he knows she has money and he knows he will benefit from it, I don't believe for a second their relationship was fair dinkum at all. Billy is a user and a liar and she's a stupid girl for not seeing beyond that.
I could be wrong, but I don't see any credible evidence to suggest their relationship is entirely built on honesty, deep down their pathetic charade is probably lies and trickery. You can't tell me that a few happy smiley photos is proof sweety? do you know for certain what is going on behind closed doors? And besides who cares about them anymore, they're finished, the next batch of BB hopefuls are on the way and the next batch of a fake romance will come along with it.