Honestly, they see life through their own prism (don’t we all). They ask you about what they are interested in. At this point, it is not your career. They want something that will further their conversation - and when you put it bluntly, you deflate the balloon of what they might have for a conversation opener.
It would be almost as if I asked you what you thought of the big football game on Sunday. If you had no interest, you might say “I don’t care”. At that point, i might feel like it is pointless talking and go on to someone else who i can discuss it.
They want you to want what they get so much satisfaction out of. And they don’t understand an alternate path.
I would try to continue a conversation without deflating their enthusiasm. (At this point, it seems that being blunt with them isn’t working)
So with the holidays coming up, i would think about how you could steer the conversation.
Auntie:"So, is there anyone special in your life right now? (wink wink).
You

with great enthusiasm) “At this point, I don’t know when I would find the time. At work, we’re busy trying to get a new product out - and that is taking me 60 hours a week. When i get home, I’m beat. But i am trying to keep in shape by joining a volley ball league - and my book club meets every month.”.
At this point, you’ve given her a few tidbits that will allow her to continue a conversation with you, and she may just follow up on it - or - if she thinks you are wasting your life, she may respond with:
Auntie:“You know, you won’t be young forever”.
You:“Thanks, that is great advice. It’s just not in the cards right now.”
But if you are interested, turn the conversation around to her.
“Why don’t you tell me about the adventures you had when you were my age? What kinds of things were you doing? How did you and uncle Jim meet? Did it take a long time to find the right person? How did you know?”
I know you are getting into territory that you are implying that you are interested in pursuing this area of discussion. But at least you are showing her that you are concerned with her life. Most people enjoy talking about their past - especially that part of their lives. And once you establish a conversation, you can gradually steer it into directions that you might want to go.