I cut my boyfriend's hair for the first time. It went well!
I tried cutting my boyfriend's hair for the first time, and it was a success!
ご質問ありがとうございます。
①
"I cut my boyfriend's hair for the first time."＝「始めて彼氏の髪を切ったよ。」
"It went well!"＝「上手く行った！」
②
"I tried cutting my boyfriend's hair for the first time"＝「彼氏の髪を始めて切ることに挑戦したよ」
"and it was a success!"＝「そしてそれは成功だったよ！」
ご参考に！
"I tried cutting his hair for the first time, and it turned out great!"
"I tried cutting his hair for the first time"（初めて彼の髪を切ってみた）というフレーズは、自然で簡潔です。"It turned out great!"（うまくいった！）と加えることで、結果が良かったことを強調できます。
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例文
1. "I cut his hair myself for the first time, and it actually looks good!"
（初めて彼の髪を自分で切ってみたけど、意外といい感じになったよ！）
2. "I gave him his first DIY haircut, and I’m so proud of how it turned out!"
（彼に初めてのセルフカットをしてあげたよ。仕上がりがすごくうまくいって嬉しい！）
3. "I tried cutting his hair, and surprisingly, it looks amazing!"
（彼の髪を切ってみたら、驚くほど良い仕上がりになったよ！）
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アメリカ合衆国 
