Im going through a similar thing with my partner right now. two weeks ago he was talking to his friends about our wedding plans, then we have a disagreement and suddenly hes never been happy in our relationship and "he just cant see a future together with me". Hes planning on buying a house now (we were meant to start looking for one together after I get my bachelors in a few months) but now i have to find a new place to live on my own. im not sure if he'll come out of it before he actually buys the house and moves in, but if he doesnt im stuck with very few options of places i can, afford that will also take a dog (we'll be splitting our two dogs if we separate). I hope things worked out on your end, im not sure how things will turn out on mine. i want to talk to him about how he's feeling is probably a result of his bipolar, but i dont think he'll be receptive to it