David Geffen and ex-husband Donovan Michaels are back together. Getty Images for Vogue

What a difference a year makes.

Last summer, David Geffen and Donovan Michaels were locked in a messy divorce that leaked into the public sphere. In fact, the former model filed a bombshell lawsuit accusing the Hollywood titan of subjecting him to painful laser hair removal and dental treatments — and then ghosting him when Michaels got sober.

But sources tell Page Six Hollywood that the two appeared to be very much back together during a high-seas outing last month on Geffen’s 454-foot mega-yacht.

The two had an acrimonious split last year that included a breach of contract lawsuit. Instagram

In June, the pair was shockingly photographed together on the vessel. Pics at that time didn’t show any PDA, but the duo appeared to be on friendly terms.

Their October reunion has surprised industry players. “The heart wants what the heart wants,” says one insider with knowledge of the (floating) palace intrigue.…