I'm noticing a situation where the developer might feel like he's bossed around by the ux designer.
It depends a lot of in the skill sets and experience of both people but in most cases the ux designer should be controlling the developer pretty heavily in order to make sure his ideas come through properly.
The UX designer may just need to work on his approach so people don't feel bossed around and more like they are working together.
In an ideal world, there would be a project manager who makes sure everything is communicated well and keeps the dynamic feeling great.