I also work among non-Jews, in an office setting. We are friendly, even sociable. When you add up the hours we spend there, compared to waking hours with family and friends, it is quite a lot. Friendly, but it ends when the business day is over. Lunch only with the same gender (except for a farewell luncheon for a retiring co-worker, very rare and with a group). Like I said, business hours only. If you feel more vulnerable, you can be strictly formal as needed.
