ANSWER:

It is permissible to stipulate this in your marriage contract. 

Sheikh, can i make it a condition in my marriage contract that my husband doesn’t remarry as long as I’m in his nikah? I know he doesn’t need permission before remarrying the second wife, but I do not want my husband to have a second wife as long as I’m with him.

Fiqh of Marriage, Marriage Contract | December 15, 2018 4:30 am
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I’m in a deadly problem. Im 21 years old running and extremely in need of Marriage. If I dont i dont get married then i fear falling into heinous sins. My parents will break their ties and i have to leave the home and cant have contact with them if i marry.