I'd like to ask for your help in these boldened lines. 優雅に脚を組み椅子に座る貴族の男と、その隣に遣えている従者。貴族の男の歳は二十代前半だろうか。耳に掛かる長さの金色の髪を後ろに流し、すっきりとし整った目鼻立ちとそれに見合った上質な衣装は気品に溢れていて、一瞬で男が高貴な身分だと分かる。 - I got confused at how long his hair is. しかしだからといってガインの事を話す訳にはいかない。ガインもしっかりとした身分を持っている男だ。名誉に関わることになるかも知れない。 - 'It may not be good to get involved'? I'm not very sure about this. The other party is a son of a Duke and ガイン is the Captain of the best Knight Order in the country. Please help.
Hmm from the description, I imagine it's a short hairstyle but not crew cut, more like a mushroom type hair, with a length that reaches the ear lobes? That's why it's sweeping behind the ears I guess... For the second one, I think it depends on the overall context? 名誉に関わること can be something like "losing face". So if they're discussing something like "You can't simply mention the Captain because of his status" is because they might not be at the same social level.
"Long golden hair that reached his ears flowed back" or something like that. "It might become something that will affect their honor" or something like that.