Is it permissible to perform the Istikhara prayer for marriage to someone one admires, without an engagement or any discussion about marriage?

Istikhara is legislated for permissible matters and is performed when one is hesitant between two options, based on the hadith: "When one of you is concerned about a matter, let him pray two rak'ahs other than the obligatory prayer, and then say..." So, if a man proposes to you, perform Istikhara regarding accepting him. However, if he does not propose, there is no Istikhara, unless you perform Istikhara regarding offering yourself to him if he is righteous, as this is permissible for a woman.