Is it possible to make a deal between 2 players as in the following scenario:

Player A owns 2 cards of a street and player B has one card. They decide to make a deal so that A owns all 3 locations but B receives 50% of the revenue A makes from that street. In addition, B does not have to pay for staying on that street.

In our case, a third player objected to this deal and as a result the deal fell through. As a possible consequence, the third player won the game.

Was the proposed deal legitimate or not?!

i cant help u there iv never played it just the bord game and that was differnt

Well in my opinion,(if your playing the board game) yes it is legit. See a deal can only be brokered through 2 players or more in a multi-way deal. The only interjection that a thrid(outside the deal) party can make would be beofre the game when setting rules. all in game trades are privey to the two(or more in some cases) parties involved. On a computer it may be different but the rule should still apply. Heck you can make any deal you want in monopoly.

By the official game rules I believe that would be an illegal maneuver. If there is collusion on the board with multiple players how would those players go about dissolving those collusions?

This happened to me last night except the two players shared two monopolies. They split the income and split the costs of improvements. this made it very easy to build and gave them an unfair advantage and they both ended up winning the game taking out three other players and unable to put each other out because they were so wealthy. I think this kind of a trade undermines the basic goal of monopoly, which is for a single person to gain an entire color set.

Deals cannot be made that promise future payment. Deals must be made for tangible items such as cash, properties, or get out of jail free cards.