This was always going to be a hard setup to make work, with one MC having a pre-existing partner for a good chunk of the book.  But as well as that, a lot of other side character conversations straddled the not-so-fine line between banter and red flag toxicity for me. 

Stopped when I realised I really wasn't enjoying any of it.  The writing was solid (though needed a little more editing), so I would happily try another book from this author -- just, with a less fraught premise.