Male and female brains are wired differently. Men tend to be more visual and use their brains more front to back and back to front; frontal lobe and visual cortex. Females tend to be more verbal, and use their brains more left to right and right to left; temporal lobes.
In dating, women pander to the male's visual strength, through enhanced beauty and makeup; visual beauty and fantasy. While men pander to the female strength through a line of bull; social strength and verbal fantasy. Pandering to strengths is part of the natural selective process.
If you look at a man and a women, from a view at the top of their heads, the differences in brain processing, is like the two legs of a cross. The male is North to South, and the female East to West.
What falling in love does is activate cross programming dynamics in the personality firmware, which are designed to create virtual male and female components within the opposite sex, so both can have the full brain cross.
A man and women who have become successfully cross programmed will be able to run on all cylinders, with the team more than the sum of its parts. They become an amalgam of each other, with this providing the virtual leg of the cross for each other. The virtual cross, by being more software than firmware is fluid and temporal; romance and connected to culture. The firmware cross is natural and timeless.
Homosexuality and transgender can go through the motions, but the brain cannot fully engage the natural cross programming dynamics. You need two opposite legs of the cross to engage the natural cross programing in both. These orientations are more based on willpower and choice, which abort the natural cross programming, since the alignment is not conducive.
A pseudo cross programming can happen, but it is more based on virtual dynamics that formed earlier in life. For example a close relationship between mother and son can form a virtual cross in her son, connected to her inner self. If well developed, he might be able to use the virtual female leg to cross program a male. But this has a degree of separation from natural, since one leg is virtual and temporal. That is not to say it cannot be effective in terms of team dynamics. However, it does not go as deep; all the way to natural man.