This Proposal Was So Sweet That Even Fiona the Hippo Couldn't Help but Stare

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This proposal was so sweet that even Fiona the hippo couldn’t help but gawk.

Read: Dive Right In! Fiona the Hippo Swims Around Zoo Enclosure and Reaches New Milestones

Hayley Roll, 22, of Sandusky, Ohio, was checking out the hippo enclosure at the Cincinnati Zoo when her boyfriend, Nick Kelble, 21, surprised her with a marriage proposal.

"Nick is really laid back so he kind of just decided that day," Roll told "No one around even knew he was going to do it."

As an onlooker photographed the pair, Fiona the hippo, a fan-favorite at the zoo, could be seen in the corner of her pond watching the first several seconds of their engagement through the glass.

Read: Stingray Hilariously Photobombs Couple's Proposal Pictures

"We're so happy Fiona could be there on our special day," Roll wrote on Instagram.