Because It Didn't 〜なくて

なくて links the missing thing directly to the feeling it caused, much like なので or のに, except the first clause here is specifically negative. 困りました almost always follows it, naming the trouble that the absence created.

Not every なくて sentence is bad news, よかった after it flips the whole thing into relief, “I’m glad this didn’t happen.” The grammar itself is neutral, it’s whatever follows, 困りました or よかったです, that decides the tone.