I can understand, it's a matter of taste, but honestly, I think I'll go down the path of "corrupting" the receptionist by exploiting her affection for the other girl, then develop the primary interest in the protagonist.
The only scenes with the two girls together will only be with the protagonist. In terms of the storyline, they won't be skippable, but visually they could be.
1) Femdom isn't planned, if i ll introduce in future will be skippable
2) they will be introduced like [EXTRA] button during scene, sothey arent plot related sothem will be skippable
3)
In the story, there will be a point where girl X is in love with Y, while Y is in love with the protagonist. The protagonist will exploit this to "corrupt" girl X, who slowly falls in love with the protagonist. By "lesbian" I mean this in terms of the plot.
In terms of threesome scenes, they will be shown, but the PURE LESBIAN scene (where the main character watches two girls do things) can be skipped; in the story, only the threesome will be mentioned.
4) lesbian sex will be optionable the main event will be the threesome
5) Probably wont be avoidable, the plot is linear.