They have no bed big enough to hold all three. The autumn night is cool on their naked bodies lying across a blanket on the beach, but Paul and Jacob are more than enough to keep her warm.
She and Paul are on their sides pressed back-to-front, curled together in the same shape as he moves in her, both with eyes closed. For now Jacob just watches, close to and facing Angela but not touching. He could be content to only watch her this way, her face looking like she's in some perfect place; his body responds to the sight almost as strongly as if he's really being touched.
She opens her eyes, intensely locking gazes with him, watching him start to stroke himself. Her hand smoothes along his chest and back as he kisses her. Paul thrusts faster, harder, shaking her body against Jacob's. Her final crying moans vibrate against his lips. Then, hardly waiting, she pulls him closer, lifts a leg over his hip. He gives a soft groan pushing in, finding euphoric relief inside her.
She is the only one in the world now who can sate either of them this way. It's only fair that they get to share.