Go Fly a Kite
Kites are usually happy things. They fly in the sky, dip, twist, and soar. But there's that pesky string holding them back. In one scene of the novel, Therese makes an elaborate obvious metaphor out of kite flying, as if we've never seen a kite before. She thinks, "the kite meant something, this particular kite, at this minute" (8.59). In case you hadn't guessed, yes, despite being in Richard's company, she's thinking of Carol in this moment. Appropriately, the kite soars—you know, just like her heart.
Until Richard cuts the string. "I can make another kite!" (8.92), he says, but still, this is the moment when Therese and Richard's relationship is cut, too. Richard may be able to make another kite, but Therese can't—there's only one person who makes her heart soar, and that's Carol. Wait, are we still talking about kites? Because Richard is heterosexual, there are dozens of kites in the sky, but for Therese, her selection is much more limited. She cherishes the kite she has, and she can't cut it (er, her?) loose willy-nilly.