Yes, all of what you are describing seem to be normal side effects of Nuva Ring.
Personally, I had all the effects you are describing (and a few more). My sex drive decreased to practically nothing and I was extra moody. My pms was severe and I was even moody other times of the month as well. My headaches increased quite a bit too.
You said "no period for 3rd cycle". Is she using the NuvaRing to skip her periods?
You also said the few times you had sex she was "not enthusiastic". I also experienced this. Even though in my head I wanted to have sex, my body wasn't interested and didn't respond the same way it did in the past (i.e. no more natural lubricant!)
It is very possible that what you describe are all side effects of the ring. Personally, I experienced none of these side effects while on combination oral contraceptives ("the pill") but women can also have side effects from the pill too. Speak with her honestly and gently about your concerns. Remember that it's not her fault. She can speak to her doctor about her symptoms and other options for birth control.
Hope that helps.