ことだし

since

→ こと
phrase Rare #29,676
since Used to give a reason or circumstance, often with the implication that it is a good time to take an action. It can also suggest “now that...” or “given that...”.
JA: 今日は天気もいいことだし、公園に行こう。
EN: Since the weather is nice today, let’s go to the park.

私が体験したことだしニコの写真もある

I experienced it myself, and I have photos of Nico too.

— 嵐の中で (2018)

降ってることだし帰らない

It’s raining too, so I should head home.

僕ら友達になったことだし石田くんこっちこっち

Now that we're friends, Ishida, over here, over here!

— 映画 聲の形 (2016)

今やジャズ好きになったことだしだろ

Now that you're a jazz fan, right?

— ラ・ラ・ランド (2016)

自分が決めたことだし後悔はない

It was my decision, so I have no regrets.

自分が決めたことだし後悔していない

It was my decision, so I don't regret it.