Photos emerged this week of Orlando and Selena sharing a hug as they partied together in Las Vegas, which raised eyebrows as Orlando's dating popstar Katy.
But Katy's now come out in defence of her man, tweeting a link to his charity work alongside the caption: "Instead of giving energy and eyeballs to dumb conspiracy check out how cool this is."
She added: "#dontfeedthebeast"
The charity work Katy linked to was Orlando's recent visit to eastern Ukraine in his capacity as a UNICEF Goodwill Ambassador, where he investigated how education can change lives after a disaster.
Selena responded by retweeting Katy's message with a praise emoji.
The former Disney star, 23, had been in Las Vegas to kick off her latest tour in support of new album Revival featuring the single 'Good For You.'
A source previously told Us Weekly: "Nothing happened. It was totally nothing and harmless with Selena. [Orlando] was in town and came to say 'Hi' to their manager. That night, they all left in the same car with their manager, got hamburgers and then each went home separately."
Katy, 31, and Orlando, 39, have been dating since the start of the year but have kept their romance relatively under wraps.