いたらなあ

if only … had

→ 居る
phrase Uncommon #11,543
if only … had Expresses regret or a wish about something in the past. The preceding verb is usually in the past conditional form.
JA: もっと勉強していたらなあ。
EN: I wish I had studied more.

医者がもう少し早く来てくれてさえいたらなあ。

If only the doctor had come a little sooner.

彼は昨晩劇場へ行っていたらなあと思っている。

He wishes he had gone to the theater last night.

昨日他の人たちと一緒にその試合に行っていたらなあ。

I wish I had gone to that game with the others yesterday.

あの頃親の言うことに耳を傾けていたらなあ。

I wish I had listened to my parents back then.

父がもっと長生きしていたらなあ。

I wish my father had lived longer.