I don't know about "feminized brains" so much as that the dynamics of the relationship change when two people find themselves objects of attraction. I see this in my straight male friends who are outgoing, friendly and kind until they see or meet a woman they find attractive, and they turn into conversely teenage boys unable to speak or angry incels unable to communicate. Of course, among my gay friends (including myself), we act the same way when seeing or meeting an attractive man, although I don't see the same animosity that straight men exhibit toward women — in most cases. Gay men who fuck and become friends are far more common than straight men who fuck a woman and then become friends.
For instance, I have a straight buddy from college. I've seen him through a marriage and several relationships and watched with sometimes astonishment and sometimes horror at how he treats women and how women respond to him. Many, many years ago, by happenstance, we had scheduled time off from work simultaneously, and ended up vacationing together. We both had a good time, but by the end of the trip, I realized that we were using each other as crutches; I can talk to any woman and become friendly very quickly. Night after night, we'd go out and meet people, share drinks or a meal, and as the evening progressed, after I'd broken the ice with the women in the group, he'd cozy right up and let me introduce him to the one he found attractive (or available). It became commonplace that he ended up hooking up with a woman we'd met only hours earlier.
One evening on this road trip, oh so many years ago, he and a guy who I found quite interesting were hitting it off, my gaydar was going off like a five-alarm fire siren, and so I reversed the roles and used him to "meet" this guy, and yes, he and I ended up going to his room for a wild night. My straight buddy was slightly off when we met up for (a very late) breakfast the following day, and it took some discussion but I eventually worked out that he was put off by the fact that I'd "horned in" (his words, which I found a bit surprising given the dynamic and remember as clearly as though he had just said them out loud).
Now, my buddy is straight and had no sexual interest in this guy, but was acting a bit like a jealous schoolgirl. He finally admitted that he thought my hookup was a good guy he'd like to count as a friend, whereas I treated this guy exactly the way straight buddy had treated the women I'd "introduced" him to over the years, and like all of those women and I, he was unlikely to have the opportunity to develop a friendship with my hookup because it was now "weird." When I pointed out that there was little chance I'd ever get to develop a friendship with the women I'd introduced to him, it dawned on him what had happened and why. As we've aged and met (and married) partners, our nights of going out and carousing have long ended, and we laugh about it now, but it points to one of the reasons that there are similarities between the way that gay men treat each other and straight men and women treat each other.