My own SO took off to a 300km remote town about a year ago. First I was told she will return in about two months but she soon - maybe after a month - decided to stay there. Our plans to move in together, pull up a business, our plans to marry all turned upside down when I found out she had no more interest in coming back to her hometown. To avoid our relationship to suffer from this I spent a huge amount of money to jet back and fro to said town every weekend. (I started neglecting my studies to a point where I am near uni expulsion). Imagine the strain on a bachelor student~
To repeatedly being told that "everything will be fine". Me virtually unaware of her mental condition kept fighting on a weekly basis with every cycle of hers.
The frequent fighting certainly took it's toll on our relationship, as about 3 months ago she started to split off, she came back to me though, changed. "my heart has gone far away" is what she fed to me.
Well to me nothing changed, I love her to bits and shambles still~ LDR come and go, we're still together ^^
Anyways, my point is, I have a boundary I unconsciously pulled up well over 2 years ago when we started out on this crazy odyssey.
If I ever found out she would cheat on me, that's the ultimate end of our relationship. I haven't yet ^^ so I keep going, despite the

raised due to the many stories I read on here.
Well certainly I would have done some things different if I knew about BPD before~ as I am doing now, trying to patch up things to defy that threeheaded dragon of splitting, but well it is how it is. Our relationship as it was ended long ago.
Anyways mate, follow your heart.