SIKA-141 NTR: woman in mask calls boyfriend while another man takes her

Ryoko wears a mask and still reads as a beautiful woman. She has been with her boyfriend for three years and the sex has gone flat, so she agrees to sleep with another man while on the phone with him. Afterward she argues with her boyfriend, but the fight turns them both on and they have sex in front of a stranger instead of over the phone. The boyfriend watches her meet someone new.