Neela married Michael, the African-American soldier doctor who was a regular on the show for a while, when he was on home on leave. His tour ended but he felt out of place at home and re-upped, went Iraq or Afganistan (can't recall) and was killed by an IED.
Over several episodes, you see Neela and the cast deal with his death. She even went to a war widow support group, but felt very out of place because she was against the war and against Michael going back, while the women in the group all seem blindly devoted to the military, as if having a different opinion would make their loved ones' deaths meaningless.