My femshep (UJ) is very loosely based on a friend of mine. (She knows and she's flattered). Currently she is battling cancer and she's in for a tough fight. With that in mind, I can't see any ending w/ UJ dying as a happy one. From now on she'll fight and live another day.
I won't go into the whole ending debate as it's been covered enough. Mass Effect 3 is BW's sandbox and they allow us to play in it. That's just the way it is. But we bring our own toys in the form of thoughts, feelings, prejudices, expectations and other sorts of baggage to play along. That goes for any art or entertainment. This is especially true of any story or art that asks the player to fill in the blanks as ME3 does in spades. Right after the game ended I, like many other people wanted answers to a lot of questions. Now I'm not so sure that I do. Now I know my femshep got a happy ending. I don't really care how she got it, but she did. She fought hard as she always did and lived to see another day. For now, that's all that matters.