Not so much for the random encounters, but most of the women he had a serious relationship with, were blondes.
Dr. Carol Marcus- Pre TOS later pictured in
Star Trek TWOK Ruth- A former lover from his academy years pictured in the episode
Shore Leave Areel Shaw- A former lover who prosecuted Kirk in
Court Martial Dr. Janet Wallace- A former lover, seen in
The Deadly Years The only other serious relationship in Kirk's past (that we know of) was
Dr. Janice Lester who appeared in the episode
Turnabout Intruder. As I recall, she had dirty blonde or brown hair.
While Kirk had a notorious reputation as a ladies man, it is worth mentioning that he was still on good terms with Janet Wallace and Areel Shaw.
And while things didn't work out for Kirk and Carol Marcus, it looked to me as if they still cared deeply for each other.
To me, it seems like Kirk's career choice was a complicating factor in his personal relationships. At that time in federation "history" starship captains could not take their wives aboard ship.
I have to wonder how things would have worked out for Jim Kirk had he lived in a time when he could have married Carol and taken her with him. (Most of her Genesis research could have been done aboard ship.) Plot bunny!
Sorry for the OT drabble.