Deciding that someone is not the right person to spend your life with is not throwing them away.
You might look at it as setting them free.
I talk a lot about how damaging my xah's alcoholism was to our relationship because that is what this forum is for and that is the kind of shares people are asking for. It is a family disease and it shapes everyone in the family. The other side of the coin is that I was plenty dysfunctional all on my own and got more so. I caused plenty of wreckage on my own because it is not kind or loving to stay with someone you aren't meant to be with and have misgivings about. They have a right to marry someone that loves them without reservation just as much as we do. It is deceitful to do anything else. I was deceitful. I had a secret from my husband. A very dark and hurtful one - and I even hid it from myself most of the time. Denying such a thing could be true. It was 'I should not be married to you.' 'I do not like who you are.' 'You are not right for me.' Because the drinking is part of who they are. You can't separate them. Of course I never said any of those things out loud to anyone but he must have felt it in some way and how horrible is that.