Verb (plain form) + ものを

[If only... / And yet... (regret/reproach)]

Connection: Verb (past/conditional plain form) + ものを

Usage: Expresses regret, frustration, or reproach. Two main nuances:

1. Regret: "If only X had been done, things would have been better" (often with ば/たら before ものを)
2. Reproach: "Even though X should have been the case, Y happened instead"

Often the sentence trails off, leaving the consequence implied.

Examples:

早く言えばよかったものを、黙っていたから問題になった。(If only you had said it earlier — because you kept quiet, it became a problem.)

素直に謝ればいいものを、言い訳ばかりする。(If only they would just apologize honestly — instead, they keep making excuses.)

もう少し頑張れたものを、途中で諦めてしまった。(I could have tried a bit harder, and yet I gave up halfway.)