I got my hair cut slowly and carefully by someone who wasn't used to cutting men's hair.
Even though she/he wasn't used to cutting men's hair, she/he gave me a slow and careful haircut.
(So I'll forgive the mistake of shaving my face.)
「慣れないメンズ相手にゆっくり丁寧にカットしてくれた」＝＞
"I got my hair cut slowly and carefully by someone who wasn't used to cutting mens hair."
ゆっくり丁寧に = slowly and carefully
「だから許すよ 顏剃りの失敗は」 =>
"So I'll forgive the bad shave." （顔剃りが上手ではなかった場合）
"So I'll forgive the mistake of shaving my face."（顔を剃るのが間違いだった場合）
アメリカ合衆国 
