If your boyfriend has a plan to only stay in this situation for a finite amount of time, there is reason to be understanding of his situation. However, if there is no plan for him to get back on his feet or get a male roommate, then I think you’ve got a deal breaker coming.
It’s hard to imagine he couldn’t find another living situation other than the one he has now with another woman he used to “partner” (whatever that means in your post) with.
Find out what his plans are, and if he’s not planning on leaving his living with another woman who isn’t you, then you should start dating other men who are more interested in living with only one woman: you. 🙂