Headcanon: Boromir admires strong women, and gets a bit awestruck by those in power. Not because of their sex or their title, he appreciates a woman who is capable of doing the job in what is, sadly, a male-dominated role. This may stem from his desire to see his family as the ruling family of Gondor, and especially what an amazing queen Finduilas would have been. While he imagines himself to be a royal, he is also willing to serve anyone who shares his passion and devotion for their country.