Okay, I have to go on a little rant. I get so frustrated when Rose Tyler is dismissed as being, “just a teenager.” She didn’t stay a teen forever! Come on!!
She was 19 when she met the Doctor, and she traveled with him for approximately two years. (I give it 18 months-3 years, and personally lean towards the higher end.) That means she was 21-22 when she was trapped in Pete’s World.
Then she was there for about three years–just judging by how old her brother was in SE/JE. So now she’s AT LEAST 24.
Plus she saw and did a lot in traveling with the Doctor. She was an average nineteen-year-old, but by the time they were separated, she’d matured far past her 21 years. On Krop Tor, it was Rose who took charge and got the Sanctuary Base crew working together–not Zach or Jefferson. Rose probably had more experience with dangerous situations than Zach, and she had more experience getting people to see their potential than either man.
So can we stop dismissing her as just a teenager? She was an adult woman who learned a lot travelling with the Doctor.
And just to say it–her feelings for him were not a teenage crush. They might have started as infatuation (because hello, most romantic love does!), but they deepened into something real and long-lasting. It was not puppy love.