Just a note, but if Janet is written this way just so there can be threesomes with a man, then it wasn't really necessary for her to be established as character who has been sleeping with men behind the MC's back literally for years -- she could just as well suggest that, since the MC is now "finally" starting to accept his biological role, both of them should start trying out male dicks, maybe preferably together. You'd have the same end effect, but with Janet coming across as a much more sympathetic character. Because right now you have her appear condescending, bossy and dishonest.
Of course, if that's the kind of personality you want Janet to have, then it's no problem.