the.com/on the rocks

means Served over ice (rather than neat or mixed with soda/water), or — of a relationship, deal, or plan — in a state of collapse or failure.

from The literal drinking sense is 19th-century, from spirits poured over lumps of ice, which look a bit like rocks in a glass. The metaphorical 'in trouble' sense likely comes from sailing: a ship 'on the rocks' has run aground and is being slowly, inevitably wrecked — a fate that transferred neatly to marriages and businesses by the early 20th century. The drink and the disaster sense then sat side by side, which is why bartenders have been quietly punning on broken marriages ever since.