When I was alone with this man in his car, he has me to marry him and I agreed and then I asked him to marry me and he agreed. A week later he jokingly asked me again infront of two other ..

In the name of Allah, Most Gracious, Most Merciful

Assalaamu `alaykum waRahmatullahi Wabarakatuh

As Muslims we are very fortunate to be the followers of such a Deen which is complete and comprehensive. In our daily lives we should be cautious of how we interact and socialise with people. Intermingling of sexes is not permissible in Islam, One should abstain from the opposite gender (Ghair Mahram) in order to save one’s self from Fitna and Haraam.
Secondly the act of Nikah should not be taken as a joke, Nikah is a great Sunnah of our Beloved Prophet Sallalahu Allaihi Wassalam. If one takes it to be a joke one would be sinful.

Hence there are two issues to your question:
In the first instance the Nikah would not take place due to not having any witnesses.
In the second instance if you replied in the affirmative in the presence of the two witnesses, he would become your husband and he would have to live with you bearing in mind the Shari obligations of a husband, i.e. to maintain his wife, provide shelter and clothing.

Mahr-Mithl (It is that amount of Mahr which women similar to her in her family will receive) will be binding upon the husband.

And Allah knows best

Wassalaamu `alaykum

Ml. Luqman Hansrot,
Student Darul Iftaa

Checked and Approved by:

Mufti Ebrahim Desai
Darul Iftaa