You are right. I think "weird" would be better to use and the plot could be the same.
well, ''disgusting'' comes across as harsh as in you don't like it, compared to ''unnatural'' or ''weird'' where it may convey the same but it gives off the feeling of not being very used to the sensation.
Yes, and it could also make your other significant to think that he is perceived as a weird/unnatural one. Especially since this is a love relationship between men where unfortunately is not something that the world is opened about it. So the mangaka could use it to have the same effect.
people dont even take into account that it was translated from japanese and it probably is not totally accurate because in most countries there are a lot of expressions that cannot be translated to english, english is too "simple" in that sense lacks a lot when it comes to express your feelings but it's also the reason that is easy to learn so well...
The word disgusting is used to liberally, whether you actually meant to use it or not it's going to convey the same message ┑(￣Д ￣)┍