Maria Morelli was a 23rd century Human woman, an astrophysicist and officer in the Federation Starfleet who served on board the starship USS Excelsior, and then the USS Intrepid II in the 2280s decade. (TOS comic: "Who's Who in Star Trek 2")
Once there, Morelli met a older classmate named Torin and the two of them started a serious relationship. Unfortunately, Torin chose to pursue a teaching career at the Academy and offered Morelli a post to teach astrophysics. Morelli, though tempted by the feelings she had for Torin, decided to pursue a active career pursuing the stars.
One her first assignments as a cadet had her assigned to the USS Lexington. There, Morelli was able to reach the rank of lieutenant. She then went to serve on several other short-term assignments prior to being assigned to the USS Excelsior. (TOS comic: "Who's Who in Star Trek 2")