Oh, boy... this is a delicate, land-mined filled topic.
All I can say is, Ian and Alice's relationship is never treated as rape by the narrative. Like
Simpgor said, the imbalance in power between the two as employer / maid is problematic and would be concerning in a real-life context. There would be the question of if she felt like she could refuse without consequence of losing her job.
It wouldn't be okay, especially with how bold his advances were.
However, this being a smut story, there's a heightened reality to it. Make no mistake, Ian is meant to come off as skeezy here. He's sharing a woman's photos with a friend. No matter how you cut it, he's an asshole and scumbag. That said, his relationship with Alice is indeed intended to be read as consensual. He came onto her in an over the top, porn-like way and she accepted - all told second-hand to the reader by Ian, with a dash of bravado. Again, I want to stress, coming onto your maid by exposing yourself would be absolutely gross in real life... but well, so would anything that happens in, say, ANY of the landlady-tenant-roomates games out there
Alice isn't that old (more like 50ish), but you'd be surprised at the rising STD rates in nursing homes. Seniors do have sex drives.