This research about strong bonds between women is not surprising to me at all. This is exactly what I was talking about in the
Ladies Lounge. However, any male SO of mine is going to have to share just as strong a bond with me to be my SO. Perhaps it's just less common for men to feel comfortable with such sharing because of pressure from societal conceptions of what a man should be.
On that note, I can recall being socialized to look for friends who would be "there for me," while my brother was socialized to avoid the boys who were in gangs or who did drugs.