Coworker Wants To Date Me, But I Don't Wanna Be "That Girl."

Hey guys!

I recently started my first professional office job (been working there less than a month.) There is a guy in my department who caught my eye. He's cute, nerdy, and seems to be very nice.

He also expressed a LOT of interest in me, asking me out within the first few conversations.

The problem is, not only does he work at the same company, he even works in the same department! If I stand up and turn, I can see him at his desk. I am interested in him, but I have a firm "no coworkers" rule. I've had a lot of relationship drama in the past, and with my next one, I want to keep drama to a minimum. But if we started dating, we would either have to keep it a secret or I could get labeled "that girl" that sleeps around the office!

Even worse, he broke up with his live-in ex about four months ago, but only told 1 or 2 coworkers (and he still lives with her) so everyone still thinks they're dating!

If I dated him, it would look like I was a home-wrecker.

I tried explaining these things to him, but he got very sad and said I was "friend zoning" him and just making excuses because I must not really like him. It's not true-if he wasn't a coworker, I'd date him in a New York minute! I suggested we hang out as friends and get to know each other first, but he took it

to mean we were actually going on a date!

How do I explain it to him so his feelings aren't hurt and we have a chance in the future should one of us find a different job or department?
Updates
+1 y
Just as a fun follow-up: Found out the coworker had lied about something that is a big deal to me (he claimed it was a misunderstanding.) Told him dating was for sure off the table. He flipped, said he couldn't be my friend.
Updates
+1 y
Two days later, got a text that said," Actually I think we can be friends." Now he barely talks to me, but he's texting my female friend (another newbie at work) all the time, asking her what she's up to on the weekend! Glad I decided not to date him!
Coworker Wants To Date Me, But I Don't Wanna Be "That Girl."
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