〜わけだ

道理(どうり)で寒(さむ)いわけだ。

Dōri de samui wake da.

No wonder it is cold.

わけだ is the click of understanding — the cause explains what you were seeing

窓(まど)が開(ひら)いている。寒(さむ)いわけだ。

Mado ga aite iru. Samui wake da.

The window is open. That explains the cold.

State the fact, then close with わけだ — its most typical shape

つまり、行(い)けないわけですね。

Tsumari, ikenai wake desu ne.

So in other words you cannot come.

Its other sense is in other words, used to check you followed