Can buyer/seller real estate agent collude?

Its always a possibility that they are doing something fishy, though unlikely. I would certainly ask your agent or at least let your agent know your concerns. In the past, I have had clients feel the same way and really what I was discussing with the other agent was what is important to the other party so we have all the info on the table and can come to terms where both parties are happy. Sometimes you cant make both happy, though often you can come up with solutions that accomplish both parties goal and everyone feels good about the deal.

Legally and ethically the agents are supposed to be a fiduciary to their clients. I am not sure that always happens, but that is the intent. In the northeast (right now) we are still seeing major supply shortages, and it is very rare to get a home under asking (if asking is in line with the market), so maybe what you perceive as collaboration is actually working in your favor??? I would suggest doing some investigation on your own. What are houses of the same size, condition etc selling for in your area? Is your deal significantly higher? If you ask your agent direct questions about how things have been handled, do you feel that the answers being provided are truthful? If not check with another agent in your area, to see if they would handle the situation similarly. If you still feel uncomfortable, there are ways to back out of the agreement. You may lose some deposit money (maybe not) but it might be worth that loss in the long run.