It’s not a disorder? What is it then?
It is the judgment of God revealed. The following passage shows that homosexuality is God's judgment on those who supress truth and disregard God's blessings.
Romans 1:18 For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who suppress the truth in unrighteousness,... 24 Therefore God also gave them up to uncleanness, in the lusts of their hearts, to dishonor their bodies among themselves,..
26 For this reason God gave them up to vile passions. For even their women exchanged the natural use for what is against nature. Likewise also the men, leaving the natural use of the woman, burned in their lust for one another, men with men committing what is shameful, and receiving in themselves the penalty of their error which was due.