Previous Dragon Age games didn't always let you romance whoever you wanted. In Dragon Age: Origins, Alistair and Morrigan would only get with a player character of the opposite sex, and Inquisition took it a step further, restricting two romances by race. Of course, for as long as restrictions have existed, so have mods to circumvent them, so many shacked up with the character of their choice anyway.
Solas is one of these characters. In Inquisition, he will only consider a romance with a female elf, locking humans, dwarfs, qunari, and any male character out of this arc. PC players can get around this with the Equal Opportunity Solas Romance mod from Nexus user AspenCrow, but because this isn't canon, there was no way to import these romances into The Veilguard - until now.
AspenCrow has now released a similar mod for The Veilguard: Equal Opportunity Solas 2. With this installed, the world state screen in the character creator will no longer lock you out of selecting Solas as your Inquisitor's romance option if they are anything other than a female elf.
The mod only dropped on January 19, so it still has some ways to go, with some romance...