One topic that is often raised during BDSM coaching is the question of feelings. The expression of feelings is expected from a sub. Dominant people, on the other hand, seem to believe that they are expected to have no "weak" feelings, such as fear or sadness.
In my experience showing feelings for the relationship to submissive people can be good. The Dom shows more than façade here. He shows that he is human; and every human being has feelings.
This does not mean that the Dom cries in a session. In a pure game relationship is little room for it. But in a (BDSM) relationship there should be room. The submissive partner learns that even the dominant has other sensations than the ones he/she usually shows. Especially since there is room to take care of the dominant. This need for care is important in a relationship - every dominant person takes care of its sub. I think it's good if the sub is allowed to take care of their Dom as well.
Doms often appear as tough guys, who know everything and master everything. Of course, it's nice to look up to such a person, but ultimately, it's an illusion. Isn’t it good (and realistic) to assume that the partner is a strong partner despite problems or grief? In addition, it can be a nice task for a submissive person to support the dominant and make him/her even stronger.
And if a young, inexperienced Dom doesn’t know what else to do, I find it more likable, for example, to show openly that he/she is frustrated or at a loss. Most people live SM and BDSM because they want to feel intense emotions. I think we should allow these feelings in their full range - even if they do not conform to classic Dom / Sub-stereotypes.
My answer to the original question: Yes, a Dom can and should show emotions, even if they are not of a dominant nature.