the expectation is that ...; the reason is that ...; the fact is that ...; the explanation is that ...; it is that ...
実は急いでいるのです。
Actually, I'm in a hurry, you see.
体調が悪いのですが、先に帰ります。
I'm not feeling well, so I'll head home first.
この道を選んだのは近いと聞いたからなのです。
I chose this road because I heard it was shorter.