"Demi's scared to get caught going to see Ashton at the movies - that's why she wants to view it in the privacy of her own home.
"She's even considered disguising herself and taking the plunge, but knows she'd be so embarrassed if she was caught watching it by anyone," a source told Showbizspy.
Moore and Kutcher parted ways after six years of marriage when the latter was found cheating on her.
Kutcher is currently dating long-time friend Mila Kunis.
"Demi knows there's no chance of Ashton taking her back, but she just can't seem to shake her obsession with him," she added.