Ms Wilson told the court the pair held hands but she could hear his breaths becoming shallower.
She said: "I twisted my body around and gave him mouth-to-mouth. I was telling him not to leave me and I love him."
But he told her he was dying, and Ms Wilson said he died as she tried to revive him.
The inquest, attended by his mother Sheelagh and older sister Zoe, heard Mr Alexander, who was living in London at the time of his death, was hit by two or three bullets from a high-velocity rifle.
Caroline Beasley-Murray, senior coroner for Essex, concluded that he had been unlawfully killed on November 13 last year.
