I was talking with another writer recently and we both commented on how truly odd the literary world is from the business side. In particular, it's the only business where a key piece of it, and one that relies equally on publishers and writers, could be so obtuse in their behavior.
They are like trying to get a humming bird to land in your hand.
Of course, we were talking about agents. Some, most probably, are polite and will decline what you send with politeness. However, where things seem to break down is after there has been some level of relationship building.
Late last year I sent materials to one agent who was very interested and we had a phone call. She asked for more materials and we made plans to discuss the project. Then she disappeared. I emailed. No response. I called. No response. I emailed. No response. Vanished.
It's hard to think of any other business where this is okay, but in the world of agents and publishing, this is fairly common. And who knows, I may still hear back from her even though it's been months.
People unused to this kinda-sorta-norm take these things personally and read a huge amount into them. However, there's nothing more to read into it other than the agent got distracted and whatever your project meant, it wasn't enough.
The silent rejection.
Best response; move on and when you sell your manuscript you can talk about what fool that agent was to miss out on you.