Truth
Throughout the play we see that the need for the truth is vital to Dan, Larry and Anna. They push into each other in order to discover what actually happened, the facts, regardless of the pain it causes them. Alice, on the other hand does not seek to tell the truth and this is why she breaks it off with Dan rather than telling him the truth of sleeping with Larry. Dan considers the truth to be what separates humans from animals, thus making Alice primitive, which she is okay to live with. The point Marber makes is that their truth may clarify it does not bring anyone closer.
Selfishness
Selfishness is a theme of this play in that each character selfishly follows what they want and even believe they need in their moments of pain. Feelings are followed rather than setting a course for long-term health. This leads to everyone getting what they "need" in a moment, but no one getting what they truly need in the long-run. They are more stunted because of their selfishness.
Lust
Marber's play calls acute attention to lust being the driving force behind the intimacy of these characters. Dan simply is after getting his sexual appetite fulfilled, he is a man who desires to be of great words, but understands nothing of the depth of love as he replaces it with lust. Thus, he is left empty, not whole. Larry, in a different manner seeks to have his sexual pleasures taken care of, his lust comes from a place of revenge and coldness. He's willing to sleep with someone in order to pay back another for the pain they've caused him. This leaves the characters exactly where Alice and Anna are at the end of the play: dead and alone.
