Once that respect is there the only thing you literally have to do is check in every once in a while. I know that sometimes even poly people -- who parade around town as the best communicators -- often are not, but even the types who try to plant those seeds of resentment learn quickly how effective it is to speak UP, esp when asked "how are you feeling about everything"
We learned the speak up and communicate when asked lesson last night. It was a pretty rough beginning to a night. I had only seen Plan B for a blip of time on Monday. (He came to my work) and then yesterday I asked Plan A if he was ok if we all hung out I have a friend visiting and we are going out of town for a few days so my usual wed and fri night with Plan B wasn't going to be possible so him and I were hoping to spend some time together. Plan A says sure and I'm excited thinking we'd have a fun night together.
Well Plan A really didn't want Plan B over because he thought I was still going to see him this week, forgetting that I was already planning on going out of town. So when Plan B got here Plan A had a really turd attitude, resulted in me asking Plan B to drive home after only being there 10 mins and him being very confused.
Long story short all that was needed was a 20 minute discussion and things were resolved. Plan A texted Plan B apologized and asked him to come back. We all had a great night and a lot of fun. Plan A and Plan B actually ended up hanging out most of the evening and we all went to sleep in really good moods.
We're learning how important basic communication can be.