Salam Aleikum brothers and sisters. Both Sunnis and Shias agree that the concept of temporary marriage known as Mut3a was a concept that was provided to us by the Holy Prophet (saww). The difference is in today's modern day, Shias are targeted for still following this concept. (Although many shia's will claim to be opposed to it). This video will hopefully help clarify the ideologies behind it and explain why Shias still follow it today.
Please watch with the intention of understanding and not fighting.