What is the reason for the ease of sexual arousal that leads to a feeling of uterine contraction and the discharge of a sticky white fluid? Is this considered masturbation that necessitates ghusl? And is this a touch or a whisper (from Satan)?

The sister who is asking is afflicted with obsessive whisperings (waswasah). The cure for this is to ignore them and not pay any attention to them. The fluid that is discharged from her could be from the normal vaginal moisture or madhy (pre-seminal fluid). This can be determined by circumstantial evidence: if it occurs after the arousal of sexual desire, then it is madhy; otherwise, it is vaginal moisture. Vaginal moisture invalidates ablution (wudu') but is pure, according to the more sound opinion. As for madhy, it is impure and invalidates ablution. Ritual bathing (ghusl) is not required merely by the discharge of this fluid, nor merely by the sensation of a contraction in the womb. Rather, ghusl is only required if one is certain of the discharge of many (seminal fluid).