Only a real estate attorney can advise on this situation and determine if something should be brought to action, but I will say that this can happen. Yes, the sellers and their agent handled the offer-counter offer roughly and in my opinion unprofessionally, but their agent owes their client the due diligence of finding the HIGHEST AND BEST offer for the property.
Don't take it personally. Sometimes things can get nasty. At the end of the day buyers and sellers have individual interests. Good luck in your future home search!