Reese & Oliver UNDERCOVER LOVERS

Reese Witherspoon and Oliver Haarmann are masters of the romantic rendezvous.

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They may both be legally single, but Reese Witherspoon has kept her romance with financier Oliver Haarmann mostly under wraps — and a source says it's making the affair exhilarating for the twice-divorced star. “She's found all the sneaking around exciting and romantic,” says the source of the 49-year-old, who's been linked to the private equity honcho, 57, since last July. “Oliver is super low-key — he's not comfortable parading for the cameras. But that suits Reese,” says the source, adding that the