Dungeons and Dragons

I recommend going to Disboard and then searching for dnd, dnd5e, or avrae, or else finding an invite to the Avrae discord server and looking through the latest posts in its looking-for-community channel (Avrae is a discord bot that helps automate D&D 5e gameplay, so I find it to be a convenient search term--but if ypur partner prefers other systems, Disboard probably has searchable tags for them too). Then just make sure the description also includes LGBTQ+ and you're probably golden (at least in terms of finding a community that is not vitriolic to your partner).

These communities are often "Westmarches" style, where players group up for short events, so the specific group of people playing at any given time rotates. Some servers are primarily focused on being a place to find groups for synchronous play (e.g. over voice chat for a few hours), while others focus on slow asynchronous play-by-post that has participation from each player once or twice per day. Some servers combine the two styles.

Good luck!

What timezone are we talking about? Might be helpful for suggestions.

My wife runs a large online D&D guild, with games 4-5 nights a week (not that you play in all of them, they just have that many people). They're no strangers to kicking people that cause drama, and they have several trans and non-binary members already.

I will say that they might not be able to bring their character in, as-is, if it's heavily based on "official" D&D lore and sourcebooks. The group has spent 8 years building all their own lore and tuning some homebrew rules and classes. It's mostly built on the 5e foundation, though.

I believe this is where they'd go to apply.

Some info about your partner? Age maybe? I have a group on discord. That's where I found mine(on a generic social server, but it worked).

Tell them to make inquiries to the D&D AL (Dungeons & Dragons Adventurer's League), formerly known as the RPGA (Role Playing Gamer's Association - they may have seen mention of it in promotional materials found alongside D&D 3rd Ed. manuals and other products like Dungeon Magazine, or Dragon Magazine before they stopped publication).

This is assuming that you mean D&D campaigns run online (VOIP, Discord, and/or Foundry), and not the D&D Online MMORPG, of course. Barring that, and taking your unknown geographical location into account, they may also be able to find organized/advertised gaming groups by making the rounds of all of your nearest brick and mortar gaming/comic shops. They're well known as consistent sources for tournament organization for things like Warhammer and Magic: The Gathering as official retailers of said products alongside the D&D content released by Wizards of the Coast.

Tell them that I said good luck as well.

Does it need to be online? Do you have a FLGS? Do they have a discord or a community board?

I'm in their time zone, willing to treat people as they prefer to be treated, and don't have a D&D group at the moment. If you guys get a game going, hit me up.