ものを
(Mono o)
if only / you should have (regret).
Connection rules
- +V plain / i-adj + ものを; na-adj + な + ものを; noun + の + ものを.
- +Regret / frustration over someone's inaction or wrong action.
- +Often paired with conditional: 言ってくれたらよかったものを ('if only you had told me').
Examples
1.
早く言ってくれればよかったものを。

Hayaku i te kurere ba yoka ta mono o.
If only you had told me sooner.
「if only / you should have (regret)」
2.
素直に謝ればいいものを、彼は頑なだ。

Sunao ni ayamare ba ii mono o, kare wa 頑 na da.
He should just apologize, but he's stubborn.
「if only / you should have (regret)」
Practice
If only you had consulted me, we could have solved it much more easily.
私に___、もっと簡単に解決できたのに。
Romaji also accepted