Captain James T. Kirk, before he made Captain married Motoko's sister. Motoko is well aware of his previous playboy attitude, and also dislikes that he's gone for extended periods aboard various ships, leaving her sister lonely. However, instead of being there for her sister, she chooses to run away to the Hina Inn.
Lt. Commander Worf, currently of the USS Enterprise NCC 1701-D. The Aoyomas and the Rozhenkos have been friends for years, and Worf always respected the families strength, even going so far as to incorporate some of the Aoyma technique's into his Klingon fighting style resulting in far fewer "Worf Effect" moments throughout TNG (Authour begins to mutter about bloody Ferengi taking down a Klingon warrior)
The two eventually marry about two years after the death of Alexander's mother, which leads to Tsuruko joining the family aboard the Enterprise. Knowing that her sister is constantly in danger do to her life aboard a Starfleet vessel infuriates Motoko to no end. Plus Klingon courtship is rather violent, watching Tsuruko hurl heavy objects at Worf while he dodged and recited poetry did not endear the Starfleet officer to her.
Edit: Ryu Hayabusa: Motoko hates that he can sneak up on her at will in broad daylight.
Sam Fisher: Motoko hates that he can sneak up on her at will in broad daylight.