The duo have once again been snapped looking more than a little cosy, this time outside an LA restaurant just after midnight last night.
Delta picked Darren up from Soho House where he was having dinner with a mate before driving her "friend" back to his swanky LA pad.
According to reports, she stayed the night.
The couple most recently worked together on Channel Nine's hit reality TV show The Voice.
Despite being photographed together on multiple occasions, the pair are yet to confirm they're an item, with reports suggesting Delta's "people" are less than pleased with the 27-year-old's new romance.
Darren has also denied the relationship, saying, "We are definitely not dating. We are just good friends. We have been good friends for six years, but we're definitely not dating."
Photos of the duo hiking in LA two weeks ago sold for a rumoured $10,000.
Delta's 10-month relationship with 19-year-old singer Nick Jonas ended in February this year.