Boss [M] gets openly flirty with employee after encouragement from redditor EmptyContext

I manage several people in an office and caught someone getting off at work once on my way out of the office, she and I were the last to leave. I poked my head in her office to say goodnight and she had her skirt hiked up over her hips and was rubbing away, but her eyes were closed so she didn’t see me. I was so turned on but quietly backed out of the office and jerked off in my truck before going home. I haven’t crossed the boss/employee line before.