A link to your actual gallery, rather than a screenshot and part of the code, would be much more helpful.
Do you have css styling on galleries that may clash? Have you tried removing some of the many elements of your gallery tag to find the culprit? What did you hope to achieve anyway with that many things?
It seems this issue is caused by the margin set by the gallery feature. It appears that the feature attempts to set the margins for each image such that the "main subject" is centered. However, in some of your images, the faces are so close to one side of the picture that the image's edge is in the window of visibility.