5週2日目 あの人のことだから
Evaluation・cause・basis
接続：普通形＋ことだし
for the same reason; List a reason
注意 / Note：State ONE of many reasons, implying «that's it and this» - so often go with も in the first part and with a suggestion in the second part. Lighter and softer than 〜から, used when you want to entice or finish smoothly.
比較 / Compare：Same song: 〜ことだから／〜ものだから. These models are often mistakenly chosen for each other — carefully read the 接続 and nuances above and then decide.
よく出る形 / Common form：普通形＋ことだし、〜。The preceding clause often has も. The latter is usually 〜(よ)う・〜ませんか・〜ことにする.
雨も降っていることだし、今日は帰ろう。
It's also raining so let's go home today.
時間も遅いことだし、続きは明日にしよう。
It's already late so let's continue tomorrow.
みんな集まったことだし、そろそろ始めましょうか。
Everyone's here, let's get started, shall we?