And when the term "sex" is used in conjunction with Gay people, it overarches all other facets of Gay people; potential Straight allies focus on the sexual aspects and features of Gay people rather than on the love that two people of the same sex feel toward each other.
Rather than use "sexual orientation" to characterize Gay and Straight people, it would be more accurate and profitable to use the term "affectional orientation." That term far more accurately determines the nature of same-sex love and opposite-sex love! And sexual relations, save for promiscuous ones, are byproducts of affection; enable long-term marriages, be they Gay or Straight.
What makes people heterosexual is the affectional relations that they have for each other! Indeed, a person is heterosexual even if he/she can't have sexual relations. The same thing is true for Gay people! One is Gay whether or not he/she can have sexual relations!
So, it seems to me that it would be far more profitable and accurate for people to use the term "affectional orientation" rather than "sexual orientation" to characterize the intimate relationships that people have with one another.