By brother Tripoly sunni:

السؤال: ما حکم الزواج المنقطع ببوذیة نطقت الشهادتین بغرض الزواج ثم عادت الی دینها بعد انقضاء مدة العقد؟
الجواب: الزواج صحيح ان لم یظهر منها ما یخالف الشهادتین.

Question (3): What is the ruling regarding Temporary Mutah Marriage from a Buddhist woman Who utters the Shahadah for the sake of this marriage and then returns to her original religion after the time of the Mutah contract ends?
Answer: This marriage is correct as long as she does nothing to contradict the Shahadah.

– end –

So the buddhist has no problem uttering the shahadah, then she sleeps with the faithful shia muqalid of Sistani,  and makes a couple of bucks, then right after the contract ends she returns to her Kufr… That is a correct Islamic marriage according to sistani!!!

So twelvers whenever you want make zinah with anyone, just tell that communist adulteress to utter the shahadah just for the time being until the zinah contract ends.