I'm gay, and I struggle with this a lot. Let's be clear about what this is prohibiting--only cohabitational acts, not necessarily relationships. But the halacha extends further---the verses in Acharei describe more accurately the partners to which one may not be married as well. Let's look a little closer at halacha later, though. For now: let's look at Tanakh as I am wont to do: through a literary and geopolitical lens, informing the mesorah we hold dear.
(4) Impetuous as water, you cannot be foremost, for you ascended your father's bed; thus you desecrated He Who ascended my couch.
Evidently, "mishkevei" means "bed", or "place of repose". So then, what would the pasuk in Vayikra mean, in this light? "And with a male, you shall not lie, on a woman's place of rest, it is an abomination". That's very different. Moreover, I won't show this inside, but you can look it up (Shabbat 55b), Re'uven's sin, the Torah says, was sleeping with Bilhah, but the Gemara derives from the context of that verse that it cannot be literal--rather, Re'uven moved his father's bed from Bilhah's tent into Leah's tent. Disturbing his father's sleeping arrangements, and getting involved in and disturbing a relationship, was something that was a) compared to forbidden intercourse and b) wrapped up in the meaning of the word "mishkevei". Evidently, this pasuk refers to disrupting a pre-existing relationship in some sense.
According to Bar Kappara, the word "to'eiva" is less "abomination" and rather something that will lead one astray. How so? If someone is unmarried, how is mishkav zachur leading someone astray? If it would enter your mind to say to a sin, then let the Torah say those who do have committed a "to'eiva". Or perhaps, call all aveiros "to'eivos". Apparently, it is forbidden for already being a "to'eiva"--a deviation from a relationship or proclivity someone already has. In essence, I posit that a faithful reading of Tanach may be to see this verse as referring to men in relationships with women already, for whom a gay relationship would be a deviation, an intrusion into a relationship, like Re'uven's sin.
Now, we come to the halacha. I want no one to go away with the idea that I am challenging the halacha as established, or that I would posit permitting mishkav zachur. For one, I am biased. For another, I do not have Yadin Yadin semicha (yet). And finally, the binding halacha is not changed by the interpretations of laypeople. It simply is not. To quote Rabbi Hain (teacher of mine at SAR High School): "I'm not one of those wackos who paskens halacha for myself". A rabbi with full semicha and commitment to mesorah making an innovation, like Rav Moshe Feinstein, Ezra HaSofer, Rabbi Ethan Tucker, or Rav Chaim Kanievsky (in no particular order) is not the same. So then, why do we bind so tightly to halacha? What is the importance in Judaism of rules that often times cause difficulty or make little sense at face value?
What is required of the Kohen Gadol? Certain ritual! He needs to do things correctly; he may not enter the Holy improperly, not even missing a spice of the incense! Why? Why does G-d care? As Iyov says:
If your transgressions are many,
How do you affect Him?
What do you give Him;
What does He receive from your hand?
The answer is in our parsha:
These things happen to the Kohen Gadol because Hashem is revealed in the Dvir, the Holy. There is a respect demanded of us for Hashem. This is the essence of the strictness and sometimes incomprehensibility of halacha. Say, you go to the Queen's Palace (Queen Elizabeth II lives at the time of this writing). You must wear certain clothes, not eat until she eats, not speak until she speaks, and so on. We are already familiar with respect being required for people and beings. Hashem deserves all that and more--why should He deserve any less? He is the Almighty, the Eternal One, the One Who Said Unto the Sea, Thus Far Shall You Come--of course He deserves the highest honor. This omnipotence does not signify that he shouldn't care--it's exactly why He can and should demand these things of us. We see this even more in our first pasuk of this parsha:
Nadav and Avihu "approached too close" and did not survive. The respect demanded of humans for G-d is echoed in the commands of G-d following the deaths of Nadav and Avihu:
(6) And Moses said to Aaron and to his sons Eleazar and Ithamar, “Do not bare your heads and do not rend your clothes, lest you die and He become angry with the whole community; but your kin, all the house of Israel, shall bewail the burning that ה' has wrought.
Now wait just a minute. I get it, Hashem needs respect. But... why does it say "lest... He become angry with the whole community"? Even if you accept that G-d has the right to demand honor, which He does, why would people who did not violate His honor be punished? How does that make sense? Luckily for you, Chazal were bothered by the same thing. Says the Sifra:
(מא) [מא] "ובגדיכם לא תפרומו" – לא תקרעו בגדיכם. "ולא תמותו" – ממשמע לאו אתה שומע הין "ועל כל העדה יקצוף ואחיכם כל בית ישראל יבכו" – זה מקרא מסורס ואין ראוי לומר אלא "אחיכם יבכו ועל כל העדה לא יקצוף" – הא אם אין אחיכם בוכים יקצוף על כל העדה.
"And your clothes you shall not rend"-- do not tear your clothes. "And you shall not die"--from the negative, you have the implicit positive [that is, if you do practice these acts of mourning, like tearing clothes, you will die]. "And upon the entire community He will become angry, and your brethren the entire House of Israel shall mourn"--this is an inverted verse, and it only makes sense to read it backwards, and say "and your brethren, the entire House of Israel shall mourn, and He will not become angry with the whole community"--that is to say, if your brethren dare not mourn, He will be angry with the whole community.
Aha. Not for not respecting Hashem--for not respecting Nadav and Avihu. The same respect due Hashem by the Kohanim MUST be shown to Nadav and Avihu, albeit by B'nei Yisra'el. Thus we see, the preface of the parsha refers us back to this idea of respect and honor--hinting that it is not just honor due G-d, but honor due each and every human being. Just as the Kohanim would have died for not respecting the sanctity of Hashem through the anointing oil which was on their heads, B'nei Yisra'el would have died if they dared not to mourn, if they had the audacity to treat the lives of others lightly. We can now revisit the idea of people struggling with halacha, in particular, mishkav zachur: people who have different struggles with halachos MUST be welcomed, accepted, appreciated, respected, and dignified--refusing to do so would violate the respect Hashem demands we give others--the respect that is the same as the respect required for Hashem Himself. As for me, I don't think of this as something I am forced to confront. Rather, I get to struggle with Hashem, I get the privilege of a relationship with Judaism and G-d that means something because it is work, and not always easy. "Ashreini, mah tov chelki, mah na'im gorali"--"Fortunate am I, how good is my portion, and how pleasant my lot!"