Looking for an old show

I'm looking for this animated cartoon, it might be an anime for all I know.
It's about these four kids, a blond boy with glasses in a blue shirt or turtle neck, a girl with short black hair and wore all black, a guy with brown hair and wore a green t-shirt, and a girl with short pink hair. There are other characters, but these are the main four.
The girl in all black and the guy with brown hair, I don't know if they were dating, but I do know they were in love with each other. Another girl, tall, long black hair, dressed in pink and wore a (maybe maroon) skirt, had a crush on the guy with brown hair, but I don't remember how she went about with her crush. I'm not sure if she was open and he was oblivious, or if she wasn't open about it.
The boy with glasses and the girl with pink hair are in love with each other. The girl with pink hair is stuck in a computer.
I know she wasn't always in a computer; she gets flashbacks/nightmares of being chased by wolves in the real world from when she was younger.
The main four have this ability: the boy with glasses mans the machine, the girl with black hair and the boy with brown go into these metallic holding tubes that transport them into the computer world. While those two fight off the monsters, the girl with pink hair does something in the main system, shutting down the world so it doesn't open again.
In one episode, while the three present a cake to the girl with pink hair for her birthday, the girl with long black hair is seen outside their room, muttering "It's just a computer," while they sing. She doesn't see the girl with pink hair.
In one of the later (or middle, for all I know) episodes, the girl with pink hair ends up outside the computer, with a human body.
I really miss this show, but I can't even mention it to anyone because I don't know the name. Does anyone remember it? Please tell me the name of this show if you do. Even a character name would be fine!