It may not have been a deception - they may truly have wanted this to work out. I wouldn't start going down that road... instead I would try to look forwards, as to what you need out of this relationship. If you aren't getting what you need, then they need to know about it.
And I'm sorry, but "things will get better" isn't an answer. The response to that should be "please tell me what is changing so that things will get better, because as they are going right now I don't see how they can."
"Things will get better" sounds like "be quiet and let us get on with what we want to do and stop bothering us".
Please check out The Birdcage - an open, friendly Polyamory forum for all parts of New York State
"Listen, or your tongue will make you deaf." - Native American Proverb