I think you’re spot on. It benefits him to be with her. Looking at his instagram heads on he always put photos of himself - you’d assume he was single till you swipe in.
he doesn’t have to disclose that the trips are ads. He gets free holidays, free flights, free events, free meals in London, sometimes premiers, she seems to get paid ads for clothes washing tables, day to day supplies, gifted products for her flat. He probably has minimal outgoings, a well paid job and a flat fairly central. I’d say it’s advantageous to be with her but there’s something off in their body language or the way it’s her clinging to him etc