Secret Hookup at the Gym

I’ve always been proud of my professionalism and work ethic as a personal trainer. My clients trust me to help them reach their fitness goals, and I take that seriously. But there’s one thing I never thought would happen, my boss, Rachel, she's in her thirties, started flirting with me behind closed doors at the gym. It started innocently enough with compliments on my workouts and how I was shaping up our clients’ bodies. Then, it escalated to suggestive comments about my stamina and strength. One day, we were alone after hours doing inventory, and she leaned in close as if she had something important to say. Instead of work talk, her hand slipped into mine, and she pulled me towards the back room where nobody could see or hear us. We ended up kissing, and it felt like an electric current running through my body. Since then, we’ve kept it a secret, sneaking around when my wife is out of town for business trips. I love my wife but feel this strange pull to Rachel that feels dangerous yet exhilarating at the same time. Is what I’m doing wrong? Am I just seeking excitement in my life or crossing a line?