This is wrong, as a romantic ace I can tell you that is is very wrong, my aesthetic attraction is much narrower than my romantic attraction.
That being said, I never talk about my aesthetic orientation, because people do just not understand that people I think look attractive have nothing to do with the people I actually fall in love with. The majority just can´t comphrehend this. Just like the majority have a really hard time understanding the difference between ace and aro.
Peopole like this do exist, I have met them in the outskirts of ace communties or non-binary communities on the internet, but they are rare. And the fact that you need to go to the outskirts of such communities says something about how rare it is to openly identify as such.
If you are not of either the ace, aro, any kind of bi/pan or non-binary or that specific experience, I would question writing such a character because it is a path full of pitfalls. And it is really hard to a person who doesn´t experience any sexual, romantic or genderfluidity to understand what it feels like to not have all your axes of attraction line up.
Personally, I would think that is would be too complex for me, and I do experience some split, though nothing that big, to dare describe in a if-game, since it is such a complex issue.
First of all you need to thínk about how this man talks about himself. Most people who experience such a mitchmatch a met with a collosal amount of gatekeeping from the community and thus rarely speak about their whole identity at once.
He would most likely either identify himself as a pan who just doesn´t sleep with women or a gay man (and just not mention that he sometimes gets crushes on women). Or he would just identify as queer and avoid further details.
Secondly, if this is a part of a poly relationship not everyone in the relation needs to be equally involved with everyone.
Thirdly gay guys are not the first one who should be reached out towards here. (Well, it is good to get their opinion too), but the primary person you are writing about is people who have a mitchmatch between romatic and sexual orientation so you need to find someone who experiences this.
In conclusion, I really think that this is too complex to be able to be handled in an if (because this is something a lot of people just don´t understand. Just look at the emotional reaction in this thread) and I would just have the character self-identify as queer and not make it an equal triad.
But even if we restrict ourselves to men, I’ve definitely experienced romantic and sexual attraction feeling different and not always coinciding… They’re not always completely the same thing.