Dear Carolyn: For the past year I've been engaged to a wonderful woman who I've known for over three years. I've recently developed strong feelings for a younger colleague who I started mentoring. She is married and as far as I can tell the marriage is okay. She is very attractive and I also find her extremely intelligent and engaging. We're both introverts but interacting with her refreshes me in a way I have not experienced in a long time.

We have been working long days together on a high-priority project, and I get the impression both of us are holding back about our mutual attraction. Sometimes I catch her looking at me in a way that seems to indicate she's also thinking about me all of the time. The nature of our job requires that we spend a lot of time in close proximity, making it increasingly impossible to ignore how I feel about her.

I don't know what to do or what my next move should be. When I go home, I'm reminded of how great my fiancee is and I feel guilty for this incredible attraction to my colleague, but I can't help how I feel. This project will be continuing on and I am worried I will say something to make things awkward between us, but I'm also worried that if I don't say anything I'll always wonder what might have been. What should I do?

— Speak Up or Forever Hold My Peace

Speak Up or Forever Hold My Peace: Wait a minute. Your possible to-do list is all about what you say or don’t say or feel or don’t feel about your colleague — but your focus belongs on your fiancee.

She can be great, brilliant, Best in Planet, and still not be right for you.

Is that what is going on here? Or, I should say, is that what your attraction to your colleague is trying to tell you?

Crushes happen, obviously, and I could run testimonials all day from people still happily married who have endured passing extramarital crushes, even intense ones. So, you could easily find yourself reading this a year from now mystified that you ever found this colleague attractive.

But you’re not married yet — so I think you have an obligation, to yourself and your fiancee, to ask yourself if being so “refreshed” by someone else means you got engaged to the wrong person — or just prematurely, before you knew what kind of connection to a person was possible. Mentally put your choice of life partner to the challenge presented by this new information.

Do this without involving your colleague or entertaining any idea of being with her, because she’s married. And there could be legal/workplace consequences. Plus, her glances at you could just mean she’s unnerved by your glances at her. Regardless, pull back immediately. She’s a “no.”

So this rethink is not Fiancee vs. Colleague, it’s about whether you need to free yourself to find elsewhere the kind of feelings you now realize are possible — or whether your imagination is having itself a fling.

It’s also the right thing to do for your fiancee, who we can safely presume wants to be your uncontested top choice. And would rather know now, not five years from now, if she isn’t.

Write to Carolyn Hax at tellme@washpost.com. Get her column delivered to your inbox each morning at wapo.st/haxpost.