Four short lines capture a very human moment: the rush of relief when someone finally shows up, followed by a sting of disappointment. The speaker starts by admitting how dull things have been, then greets a visitor with real, almost gushing happiness. But the joy doesn't last long. A question breaks in, "Wait, you have to leave tomorrow?", and the mood turns from excitement to deflation.
The last line, "That should have been clear," is the most interesting. It sounds like the speaker is scolding themselves, as if they got carried away and ignored what they already knew. It could also be a small complaint aimed at the visitor. Either way, the tone is light and casual, but there's loneliness underneath. The speaker has been bored and isolated, and even this visit comes with a deadline. The title, "When you get home," hints at waiting and distance, so the poem feels like a quick burst of happiness that's already starting to slip away.