そびれる after a ます-stem means you meant to do something and missed the moment: "missed the chance to", "never got round to". It is an ordinary る-verb, and it mostly appears in the past, often with .
、。
I meant to tell you – next week's meeting has been cancelled.
。
I was so busy I missed lunch.
、きごう?
I didn't get a chance to ask – what time does the meeting start?
The verbs you meet it with most are , , , and . is not getting to sleep because the moment passed.
、。
I drank too much coffee and couldn't get to sleep.
そびれる or なかった
A plain negative says only that it didn't happen, perhaps by choice. そびれる says you intended to and the chance slipped away.
。
I meant to call him but never did.
そびれる or 損ねる
and
after a ます-stem also mean "fail to", and cover failed attempts as well as missed chances:
is trying to catch the train and missing it. そびれる is only about letting the moment pass.
。
I missed the last train.
。
I never got the chance to say thank you.