I think the nena crossover is just a pure coincidence. In a video back in oct-nov (whatever year it was when she and destiny lived together in the townhouse), amber was all giggly over her weight loss buddy, Nena, in TN who was like her soulmate or exactly like her, or something like that (If I find the video, I'll post it below). Fast forward to Amber in her lives with Rafe, we learn that becky and Nena were together for 5 years, and Nena dumped her out of the blue in a Taco Bell. Rafe and crew hate Nena. Ok, rewind to when amber was all alone and sad over destiny, she may have had one date or so with Becky at this point, she got weight loss buddy Nena to pick her up in KY and drive her to VA to visit Krystle. I'm assuming she dangled fixing them up over Nena to get her to agree to the trip. I guess it worked, because then Krystle was driving up to visit Nena every few weeks, and for whatever reason she and Nena would then go to KY to stay with/pick up Amber so she could third-wheel it. Then Nena moved in with Krystle in VA.
Rafe gave the impression that Nena and Becky did NOT end on good terms, so I don't think it was Nena pushing Becky in Amber's direction. I think it's just one big, hefty, redneck, lesbian mafia coincidence.