Saying "No Thanks" to lunch dates...

A couple weeks ago I had a speaking engagement for work in front of a large group. Afterwards there was a brief meet and greet type deal and this guy approached me and sparked an uninteresting, full-on awkward conversation. As I was wrapping up (aka, walking away), he asked me if I ever wanted to grab lunch...in front of numerous others. Of course my business cards were on the table out front so he had my number, email address and work address, merely for business purposes, and like diarrhea of the mouth, I responded "sure", because what else would you say in that scenario?

"Oh, I'm not interested."

"No thanks, I have a boyfriend."

"I'm way too busy."

"Before I commit to this lunch, what are your intentions? Are we going to discuss business or is this an attempt to get to know one another on a personal level because that is unacceptable?"

What if he only meant a casual, platonic lunch..maybe even to talk about business (which I still can't seem to draw the connection given both of our industries).

So here's the proverbial question...What Do You Say?

I was hoping it was a rhetorical question and he never intended on calling to follow up on lunch. Maybe he ran out of things to say during our encounter and didn't want to sound rude so he casually mentioned lunch? But...no such luck. He called...and has continued to call. I have been a coward and ignoring his calls and even accidentally answering and then saying "hold on" and then hanging up. I know I know..not mature at all. But since I already said yes, how do you get out of it?

I find lunch with a man you don't really know, who isn't directly related to business at hand to be inappropriate for someone in a relationship, but how do you say that without sounding like an a$$? What if you respond to his offer "That sounds great, but I have a boyfriend" and they counter with something like "I was just going to talk to you about how you market health care in this region, you conceited biatch!" Are you supposed to ask up front "Before we go to lunch, what are your intentions?" because that sounds heinously crazy.

What is the right answer, or is there one?

.jl.