Rohm was convinced that his SA should be the premier and only military of the German Riech. Hitler thought purging the German military was a really stupid idea. The SA were too much thugs, drunkards and the higher ups being general faggots. Rohm kept disobeying and acting like he was going to what he wanted to do. The SS was the replacement for the SA.

In general, the SA and Rohm being a reckless and destabilizing force was the biggest issue. They paraded around and became belligerent with the public and thought they were a big shit now that the NSDAP was in control. As far as the gayness, it was not that in total. It was the fags in the SA command going after younger men and maybe even boys that was the final straw.