The story doesn't really make sense for the landlord to ask you to leave like this as he would have paid the agent to place you and will have to do so again that combined with any occupancy gap between you leaving and finding a higher paying tenant would probably lead to a similar net income.
Personally I believe the agent may be untrustworthy as they placed you paid for by the landlord and may be benefitting from you leaving through more income either from reletting or you offering to pay more to the landlord, which they may be supporting but telling you another story. Maybe the owner thinks you want to leave and that why the unit is on facebook.
While I agree with other comments that in these circumstances better to leave I suggest you say you will leave but want to talk with owner direct on the details of why!! Be careful as your deposit may be at risk in this process so if you agree to leave get in writing you pay no more rent and your deposit will off set the rent. Also ask for compensation as you have a cost to move. You may not get it but worth asking.