As a woman I can pretty much say with certainty that the regained feeling is actual arousal, it would make complete sense she's lost the true feeling of that from constantly being raped, the pressure of being in a tense, unwanted relationship, and likely being on the verge of doing something serious and dangerous for a long long time.
As for pregnancy, extreme stress, uterus disorders, illness, sudden weight loss or gain and carrying a baby can all stop a period. Likely thing is she's either stressed or pregnant, I'd hope not pregnant because covering rape babies is honestly horrifying.