〜にかこつけて

Meaning

Indicates acting under the pretext of something while actually having another purpose. Carries the nuance of feigning a surface reason.

Examples

仕事にかこつけて、彼はたびたび彼女に会いに行った。 Using work as a pretext, he went to see her frequently.
病気にかこつけて、面倒な集まりを欠席した。 Using illness as an excuse, he skipped the troublesome gathering.
接待にかこつけて、彼は連夜飲み歩いている。 Under the guise of entertaining clients, he goes out drinking every night.