Secondly, he never wanted Arzoo close because he couldn't marry her as he was already married. What's changed here? Nothing at all. He always had his hands tied. Surely he is thinking that by marrying Aarzoo he may give her added issues which he can't want after all of the problems he's put her through. So again I think this is part of his masterplan. Yes, Zaki's after her and he is jealous, but I feel now he has enough faith that she wouldn't marry Zaki. He knows she still loves him.
What could happen though is on the wedding day, Zaki/Sahir manage to stop Zaki's marriage to Sam as they find a way to trump Rehman but for whatever reason Arzoo still ends up marrying Sahir, although Sahir's plan may have been for that not to happen either.
The only problem I see with Sahir marrying Arzoo is that puts an end to the love triangle. If that happens what will be Zaki's larger role? May be he will work hard, become rich and return to Arzoo, asking her to leave Sahir? Could be. But one things for sure, there is no way Zaki can marry Sam if this story needs to continue. And the same goes for Zaki marrying Arzoo. In short, Zaki's going to stay single, whatever happens!
Alternatively there could be no marriage at all. Sahir manages to resolve all issues without having to resort to a bunch of forced marriages.
Finally, could be Sahir marries Arzoo, Zaki refuses to marry Sam. Rehman lets it all out and Sahir loses everything. But I doubt this could happen. What would we do without Sahir's pool bedroom??
Anyways...I feel it's all a bit up in the air at the moment. A lot if things happening they don't really make sense to me but hoping for some clarity on the whys by the end of the week.