ok, i get that there's various bodily responses to arousal - swelling due to increased blood flow to specific areas of the body, eye dilation (which is what i have to assume is meant whenever they say someone's eyes darken). hell, if activities that inflict injury are involved (scratching/biting/accidental room destruction/idfk) there can be various swelling.
but fondling someone on the body in general (ie. not on genital area) does not make that body part "plump" like a bloody rising dough.
also the book needs a second run through by an editor, noticed an instance of "boats" instead of "boots" that made me giggle.