Cote de Pablo
Cote de Pablo was a main character on NCIS. She dated Diego Serrano from 2000 until 2015. They never got married or even engaged in their long-winded relationship. Since the breakup, de Pablo has been flying solo.
Jorja Fox
Jorja Fox really tries to keep her private life just that: private. She never talks about relationships in her interviews and tries to avoid any questions about marriage. It seems like she's been single for quite a while, and she probably wants to keep it that way.