Agreed with the NRE bit. He is well in it if he thinks it's okay to tell you he loves her more... not very kind and he needs to be told this I think. He should of used his inside voice and put things into perspective more. It's important to think of it all with realism and from a wholistic point of view. It's not okay to be a dreamer with pie in the sky notions that everyone will get it just because you are feeling it. I find this to be a selfish approach that is very indicative of people that don't communicate their emotions openly. They take them inwards and think they are the only ones feeling them. Often there is not a filter when they start talking about how they feel. The good news is that he is being honest, finally, after cheating. The even better news is that it is possible to begin learning how to express oneself without causing hurt for another. You and him can learn that together, be patient and forgiving, he is in love is all.... it all dies down eventually. Given time.
The thing with poly is that one doesn't get to treat the relationship dynamic the same way as in mono ones. In mono ones we can lawl around in that lovin feeling and those on the outside might be pissed off that we missed a lunch date, but they get over it quickly because the amount of depth we have with others is not as deep.
In poly we have to consider others. We need to consider the level of respect we have, the amount of empathy/compassion we have for our partner, we need to realize that each relationship holds different energy than the other and be on top of how to handle that and respect that, we need to make sure we keep our integrity in terms of being trustworthy (no cheating!) and sticking to what we agree to and the boundaries we create and we need to be open to communicate openly and honestly with kindness and consideration for others... more where the respect part comes in...
It's a hard balance and takes practice. It does work though. If he and you really want to make this new life style work then I suggest that you both get on these things and become pro active in your relationship, otherwise it could very well be likely that he is mono and has moved on in his heart.
There is a lot of info on here that can help with that. Do a tag search (start with "NRE" maybe), look at the stickies, if you can't find what interests you and resonates with you then ask any of us mods or PM people. We are all here because we like to help and need our own help... so make use of that.
Anyone want to be friends on Facebook?
Send me your name via PM