It is never easy to be on either side of a multiple offer situation. Whether you are representing the buyer who doesn't understand why their offer wasn't selected or representing the seller who had to make the choice between offers.
Over the last few weeks I've had a couple of properties where multiple offers were received in a matter of days. The owners had some tough decisions to make. Not one that I envy them having to make. My role is to provide guidance, not make the final decision for them. I can't disclose to the buyer's agent or the buyer's why their offer wasn't selected. It's not that I'm being difficult or want you to wonder why your offer wasn't selected, it's that I can't tell you.
You see I have a duty that is clearly spelled out in the Realtor® Code of Ethics and the listing agreement the sellers signed with me to maintain the confidentiality of my client. I can disclose, if my client says it's okay that there were other offers and if those offers came my own clients, another member of my firm or a cooperating broker. But that's it.
When a property goes to settlement a buyer may get a glimpse behind the seller's selection of offers but even then I can't answer any detailed questions. I understand you are disappointed. Last year I wrote a post entitled "Highest and Best Aren't Always Synonymous" that helps sum up the dilemma that everyone sitting around the table with a stack of offers has to deal with.
I wish I could offer you more but I'm bound by ethics not to say more.