Same-sex pair skating is endorsed by ISI, but never was supported by the ISU.
The Ice Skating Institute of America (ISI) has had since its inception, testing and support for "couples" and "mixed pairs." In other words, there is an avenue for same-sex pairs to train, test and compete - but it is under ISI, not the USFS or ISU.
I was personally a victim of the ISU's stance on same-sex couples, and I was only a singles skater at the time. In 1998 at Gay Games V in Amsterdam, the organizing committee set out the structure and rules for the competition, including the judging. They patterned it after ISU rules, but never asked the ISU for permission or a sanction, and never received it. When the ISU did catch on, they reviewed the competition structure and because it contained same-sex pairs (as part of the competition) and used the 6.0 judging system without permission, they refused to sanction it.
That meant that if they continued on with the official competition, every single skater, coach and judge was at risk of losing their ISU and USFS membership (unsanctioned event participation). There were professional and elite level skaters at this event (triple-triple combinations, skaters ranked in top 10 for their country, etc) who could not risk it. Judges would not risk it at all. The committee did not consider making same-sex pairs a "demonstration" event and dug its heels in about it and the ISU never sanctioned.
The entire competition was turned into a public practice exhibition event. No medals were awarded except the participation medals. We performed and were considered athletes, but we all trained, traveled, marched in with our countries in the Opening Ceremony and were then told our place to compete was simply not to be.
It was heartbreaking for those of us who were so serious about training, representing our country at the peak of our physical abilities and sacrificing to be there.
In the future, GG wised up and has been partnered and sanctioned by ISI every single time and the event is a huge success - including same-sex pairs.
At GG VII (Chicago) I was proud to represent my country in Singles (Bronze Medal Level 5) and Mixed Pairs (Gold Medal Level 5) with my partner under these sanctions and rules. There were many same-sex couples skating, several quite seriously.