The aim of Mut'ah marriage is to save both man and woman who are not able to get married from falling in sexual sinful thoughts and acts. There is a Hadeeth from Imam Jafar Al-Sadiq (AS): In fact, Mut'ah marriage was ordained for the benefit and protection of the women who have no husbands. Married men should not indulge in Mut'ah marriage in a way which makes their wives angry and blame Shariat which allowed Mut'ah. (Al-Kaafi, V. 5, P. 453 narrated from Abul Hasan (AS)).
Wassalam.