Kate has 说 I 爱情 you, but to Kevin the guy she married.
She hasn't 说 I 爱情 你 on screen to Jack 或者 Sawyer. In the episode "Every Man For Himself" she 说 "Yes I 爱情 him!" when asked 由 that 'other dude' while Sawyer was being beaten to a pulp - though later in the episode Kate then takes back what she said.
Kate has not 说 I 爱情 你 to Jack on screen, but it's pretty easy to assume from their time together off island with their engagement that she must have 说 it to him at some point, we just haven't seen it. It's also fairly easy to assume that she is still very much in 爱情 with him, looking on her actions in season 5.
HI LISTEN AT THE END 迷失 THE 6TH SEASON SHE 说 TO JACK AT THE LAST EPISODE KATE HAD TO GO TO THE PLANE & LEAVE JACK SO SHE SAID:"TELL ME I'M GOING TO SEE 你 AGAIN AND THEN SHE KISSED JACK AND SHE 说 I 爱情 你 & JACK TOO.IT WAS THE LAST EPISODE JACK DIED IN THAT EPISODE ON THE ISLAND BUT THEY ALL LANDED IN LOS ANGELES CAUSE JULIET COULD BLOW THE BOMB & everybody landed in the los-angels at first they couldn't rem ember each other but then they could & jack & kate were together (jack + kate) so this is truth because it was 1 月 或者 2 months 以前 the finally
HII!! No, Kate has never 说 "I 爱情 you" to Jack (unfortunately), but he already 说 it to her in the end of season 3!! Kate has, however, 说 "I 爱情 you" to Sawyer in the last episode of season 4, when Sawyer was about to jump the helicopter. :/ As a jater I think she was carried 由 the moment, she probably thought she would never see him again, 或者 that he could die...