Consider letting go. During all this time that has passed you can be sure she hasn’t been spending it alone. For all you know she could be feeding you a bunch of malarkey. It may be true that she is seeing a psychiatrist but don’t take that to mean she is not seeing or dating during your period of separation. Bipolar people have serious impulse control issues, heightened reward sensitivity. Moreover, many of them are manipulative and sometimes even outright deceitful. So unless you can be sure that all she is doing is taking some time to try to treat and heal some of her challenges and nothing more, I think holding on is a mistake. She may come back, and she may not but how long are you willing to stay in limbo? Don’t forget you have a duty to YOURSELF too. Not just to her. I think far too often we confuse self sacrifice as some kind of hallmark of our virtue. It’s not. It’s emotionally infused martyrdom. It’s often a subtle way to feed our own wounded egos and our round about way of attempting to get our own needs met by sacrificing ourselves. But what happens if our “sacrifice” is not rewarded? As a hypothetical would you feel if you found that during your separation she had been out and about and dating and having sex with others, while you’re sitting at home looking at her stuff missing her and pining for her return? What if she never does? Her Bipolar Disorder is her problem to grapple with. All this “love” and “support” talk, might be real or it could also be a sign of a trauma bond, how can you cut these through the fog to tell the difference? Remember, you matter too and that shouldn’t change no matter how much you were into one another at one time, how great the emotional exchanges might have been. Be careful that your sense of well being does not deep into being dependent on what she does or does not do. I encourage you to Google the myth of the Greek Sirens. Sometimes what we hear as an ethereally beautiful and enchanting song, is illusory. And in fact is actually more like a wail of despair, if you’re a rescuer and it sounds like you could be and need to play hero to find a sense of self validation, a damsel in distress can be a real turn on both sexually and emotionally. Their vulnerability can be most alluring, but it would be a shame for you to be lead astray and miss out on all life has to offer you, abandoning the fulfillment of your own needs hoping for this girl’s return. If she doesn’t, then what?