Selena Gomez may be a fan of passive aggressive tweeting about her relationship with Justin Bieber, but one thing she won't do? Field direct questions.

The pair were said to have split just before New Year's Eve during a vacation to Mexico, and TMZ cameras harassed Gomez in the airport asking nonstop about the breakup.

Friends of fallen paparazzo Chris Guerra, who made a career out of stalking Justin Bieber, insist that he's pretty much a huge pothead -- and that the reason she and Bieber broke up is because another woman named Mary Jane came in between them.

Still, sources close to Bieber insist that the sticky icky has got nothing to do with the latest "off" in his on-again-off-again relaysh with the almost-relevant Gomez. Instead, his pals say, "It's just high school stuff."

Hey, Selena? You're 20 years old. That's what happens when you date 18-year-old boys.

Still, a pal of the couple says the split may be a permanent one.

"Justin and Selena were together for a long time. They love each other and will always care about each other, but it just isn't working between them," a friend told Radar Online. "This might really be it for the two of them. They're over going back and forth and all the fighting and reconciling. They're finally realizing that no matter how much they try to make it work, it won't right now."

Isn't that what they say every week when this happens?

As for the fight south of the border, the friend said, "Their time in Mexico was much of the same for them; constant arguments and bickering.

"So they ended it. Selena is Justin's first love and he's still young enough that he desperately tries to make it work. But Selena is mature enough to just know when to end it and be realistic that it isn't working."

Don't think Gomez was crying and playing 'Baby' on repeat over it, either. "Selena didn't wallow in their breakup," the friend said. "She went out New Year's Eve and had fun with her friends and did her thing. They're both better off to just move on and go their separate ways."

We're sure they will. Probably right after Gomez's next few movies have peaked at the box office.