As you may all know, same-sex marriage in the US is legal and binding between parties and between states. There is no more prohibition for marriages between two same-sex individuals and all the rights, duties, and responsibilities that arise from the contract of marriage are also afforded to these individuals.
In immigration law, same-sex marriage is treated similarly as opposite-sex marriage, thus, I-130 petitions based on marriages between two men or two women are to be decided based on the existence of bona fide marital relationship. This procedure extends to fiancée visa petitions as well.
I have worked on petitions that involve same-sex couples between Filipinos. While same-sex marriage is illegal in the Philippines as being against public morals and public policy, this prohibition is sidestepped if the same-sex marriage is between a Filipino and a former Filipino who is a naturalized American citizen. US immigration law does not care if you were a former Filipino citizen and the Philippines does not recognize same-sex marriage. As long as you are an American citizen and there is a bona fide relationship between you and your Filipino spouse or fiancée, your spousal petition or your fiancée visa petition will still be approved.
Take the case of Lucy and Norma. They were sweethearts since high school, lived together, and are madly in love with each other. The only problem is that Norma is a citizen and resident of the Philippines. Lucy, the former Filipino citizen, is now an American but cannot marry Norma in the Philippines. What they did was that Lucy petitioned Norma under fiancée visa, and once we had it approved Norma came to the US and they got married in Las Vegas. Lucy then filed a spousal petition for Norma. Norma later obtained permanent residency.
You may wonder, do same-sex petitions open up chances for immigration fraud? That is a possibility, but there is no statistical basis for that which I could find. Same-sex petitions are scrutinized just as rigorously as the traditional form of marriage.
It may be impossible for gay men or women to get married in the Philippines under the present times or ever, but there is a way, as illustrated above, that same-sex couples can still get married and be endowed with all the legal effects of marriage. The only caveat is that even if you are married in the US, the Philippines will never recognize your marriage and as such, you have very limited rights or even none at all.