Under the pretext of / Using (N) as an excuse
Indicates that someone uses a noun as an excuse or justification for their actions, often in a negative sense (formal/literary).
Examples
彼は仕事のストレスにかこつけて、飲みすぎている。
He is using work stress as an excuse to drink too much.
忙しさにかこつけて、約束を破った。
Using busyness as an excuse, I broke my promise.
彼女は体調不良にかこつけて、会議に出席しなかった。
She used her poor health as an excuse to skip the meeting.
Quick check
彼は仕事のストレス___、飲みすぎている。