She had enjoyed Mrs.Vance's companionship so much.

There was no one else in the house whom she knew.
Again she would be all alone.
Hurstwood's gloom over the slight decrease in profits and the departure of the Vances came together.

So Carrie had loneliness and this mood of her husband to enjoy at the same time.

It was a grievous thing.

She became restless and dissatisfied, not exactly, as she thought, with Hurstwood, but with life.