申し訳

1. Origins, structure, and basic meaning

• Structure: 申し訳 is read as もうしわけ and is a noun for an excuse, justification, or grounds for saving face, appearing here in two negative idioms.
• Basic usage: It strongly states that lateness or a broken promise leaves no excuse or way to justify oneself.

2. Common pitfalls and similar expressions

• しようもない
  • 申し訳のしようもない means there is no possible way to offer an excuse; しよう here denotes a method.
• が立たない
  • 申し訳が立たない means that no justification or face-saving explanation will stand, not simply that an apology was spoken.