Beryl sent Kori to swim the oceans, looking for her people. They would rendezvous in two years time at the rocks by Cintra's waters. She joined Geralt in his journey, hoping to find some mer-folk on land - just as she was on land. Once the time neared, she had to leave Geralt. She valued her time spent with him, but it was time for her to engage in another war - the final war.
As promised, within two years, Beryl traveled back to the rocks by Cintra's waters with Geralt. He subtly insisted on escorting her there. She was happy he did so. In two years, Geralt still hadn't managed to save Beryl's life. She was a smart girl, and she knew it was a good thing that a Witcher owed her a favor. She counted one of the two favors he owed her to be when he stuck around with her and Kori. Geralt had casually said that him escorting her back to Cintra was free of charge - that he could still try to find business on the way there and back.
When Beryl went to the rocks, she nearly cried. There were one hundred or so mer-folk still alive. It wasn't as much as Fiopha had before, but it was enough. Combined with Cintra's soldiers, Beryl would make it work - she had to.
Before she stepped in the water, she turned back to look at Geralt and flung herself at him, wrapping her arms around his neck and kissing him on the lips. Geralt staggered back from shock, but wrapped an arm around her waist, reciprocating the kiss.
The mer-folk in the waters looked at each other and slowly sunk down, giving the two some privacy as they attacked each other's faces.
Beryl looked at Geralt and smiled. "If I'm still alive by the end of this, I'm coming for you."
He chuckled. "And I'll welcome you back."