It's kind of silly when you think about it.
If you do as much traveling and consulting as I do (which fortunately I don't have to do much anymore) I used to eat alone a lot. In fact, I have gone to Movies by myself. But on the other hand, it also provided me the time to read a lot of books as well. I don't believe the stigma is as much today as it used to be, but maybe I am just used to it.
I rarely eat alone in a restaurant when I'm near my house, and I rarely travel alone, so I understand your dilemma. I have gotten to the point where I will if I'm out and about and just need some food, but it's very utilitarian. I don't think I've ever eaten alone anywhere other than a fast food restaurant.
It's just not the same experience as lingering over dinner with friends and conversation. Maybe it's something I should do more often, I don't ever judge someone eating by themselves in a restaurant, but it just doesn't seem right. It might be interested to intentionally visit some restaurants alone just to have the experience.
There is something worse; eating alone on a business trip, at night, in San Diego, at a Denny’s. Nothing else is open. The town is without a good diner..