Am I allowed to not want a husband who posts on social media for entertainment, such as photos of himself (profile photos or stories of what he is doing)? I prefer a private life and worry about fitnah, self-display, and seeking outside validation. Is it Islamically valid to have this preference?

Ustadh AbdulAziz al-Haqqan

Yes, you may refuse for this and you are not sinful, because a woman is not compelled in marriage and she knows her own situation best. Photographing and posting is itself a matter the scholars differ over.