One of the points where Voyager approached distinction, in terms of the drama it brought to the table, was the flirtation that Tom and Kes had. I consider it a missed opportunity that VOY couldn't bring itself to depict Tom and Kes having an affair, at least outside the fig leaf of an alternate future. Flawed characters, thy name is not Star Trek.
When B'Elanna died in another timeline, Kes came to Tom's rescue, helping him cope with the mental anguish. She helped Tom recognize that he could and would move on - that he'd learn to fall in love, again ... because he can.
Of course, she was totally right. Tom did find love, again - and so did she: with eachother!
In fact, this episode had Kes - and the audience - review her life on Voyager, up to that point and it became clear that Kes, was indeed, more important than we realized. Because this type of support she showed not just for Tom, but the rest of the crew, is so typical of Kes. And it was vital to several characters' development on the show, particularly the EMH. In fact, the Doctor would've been incapable of offering much guidance to Seven, whatsoever, had it not been for Kes' patience, warmth and friendship.
Kes seemed to have a very good rapport with the good Captain and she was very loyal to Janeway, besides. In my view, Kes was Janeway's guide ... and her conscience. She wasn't just "all heart," either. No. Kes had a strength. In her was a power I can't pretend to understand, but one which Tuvok tried to help her master. And, because of her unique life-cyle, Kes never lost her sense of wonder at the world around her and, in fact, the entire universe. Something too easily lost and even dismissed, by most of us, in our own lives.
Unfortunately, the writers wrote all of this off in favour of a fanboy fantasy woman of the bimbo variety.