I was studying the lyrics of the music 「私の声」and I notice the use of the verb 行ってしまった that seems to be translated as something like ‘has gone’. At first glance, I thought it was the past tense of 行ってします, but doesn’t it should be 行ってしました? I couldn`t identify this conjugation, could someone help me?
It’s the past tense of 行ってしまう, which in turn is just 行って + しまう, where しまう is an auxiliary verb which has a few connotations, like doing something by accident (usually not with good results) or is “done completely” (in the absolute vaguest sense possible, I have no idea how to actually explain it in English).
Also, if you ever see a conjugation ending in ちゃう (or a conjugation thereof), that’s a contraction of てしまう - so 寝ちゃった = 寝てしまった = “I fell asleep”