Never thought of myself as a "nice guy" but I used to micromanage my interactions so that I would never "hurt" the other person (make them feel bad in any way) and it resulted in a comforting false persona that other people learned to rely upon. However, it was impossible to maintain, and so I eventually let them all down, resulting in deeper hurt than if I'd just let myself be a little less gentle. Took a while for that guilt to solidify into honesty but it did eventually.