Rosacea is a cosmetic condition characterized by consistent redness in the face.  It occurs when the blood flow through the blood vessels in the skin increases, giving the face a flushed appearance.   Now, there are literally dozens of reasons why the face would become flushed.  When I go running, my face gets red.  If I do something stupid, my face gets red.  The first time I kissed a girl, my face got red.  Pretty much any time that I am involved in a stressful situation, my face gets flushed with a touch of pink.  From a technical standpoint, this is part of my fight or flight response governed by my autonomic/automatic nerve system.  In situations of stress, my blood gets pumping more so than normal.  And stress is stress, no matter if I'm running from a pack of wild hyenas or sitting on the couch watching NC State lose another basketball game :( - it is what it is. 

Once that fight or flight response goes away, though, my blood flow should be able to return back to a normal.  If I'm out of that stressful situation, why would I need extra blood flow?  Why would the increased blood flow to my face (technically called erythema) remain?  Well, your nerve system is as complex as it is simple.  When you get into the nuts and bolts of your body's neurology, you'll realize that if the hub of your nerve system (the brainstem) is being interfered with, it'll have a variety of abnormal effects on the body, much like interfering with a satellite that controls your TV reception causes the picture to look distorted, or the audio to cut in and out, or any of the other myriad of effects.  An emotional stress can cause the fight or flight response, but so can a physical a misalignment of the bone that protects the brainstem.  Again, stress is stress. 

Remove the tension on the nerve system hub and get your emotional stress under control, and tell me why the redness in the face wouldn't go away?