Late Night Office Encounters

I've been teaching high school for a decade now, married to my wonderful partner of seven years. We lead a comfortable life and share similar values about relationships and fidelity. However, over the past few months, I've found myself drawn to the office after hours, often staying behind well past when most colleagues have left. It's not just idle chatter or after-work drinks, I find myself feeling strangely energized by these solitary sessions, writing lesson plans in a room filled with the lingering warmth of others' presence. What puzzles me is that I've started to imagine scenarios beyond mere professional reflection, fantasies involving someone else, someone younger and more vibrant. I know this isn't something real or planned; it's merely a mental escape. But why am I compelled to indulge in these thoughts? Am I seeking an alternative reality where I'm not just a teacher but also an adventurer or a lover? Is it common for married individuals to find themselves drifting into such uncharted territories of the mind? Should I seek counseling, or is this simply a part of navigating adult relationships and professional life simultaneously?