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not writing or contacting for a while; neglecting to write (call, visit, etc.); failing to write (call, visit, etc.); long silence
長い間ご無沙汰していて申し訳ありません。
I'm sorry for not being in touch for a long time.
無沙汰を詫びるために手紙を書くことにした。
I decided to write a letter to apologize for not being in touch.
友人に無沙汰していたので連絡してみよう。
I haven't been in touch with my friend, so I'll contact them.