It's best to avoid anyone who uses either alcohol or pot or both. Often all you become is just some other high and that's not healthy for anyone as you are only secondary to whatever drug is being used as some kind of coping aide.

Also, what many do not know about is how THC in pot can lead to a person having psychotic episodes and paranoia.

paranoia is a mental condition characterized by delusions of persecution, unwarranted jealousy, or exaggerated self -importance, typically elaborated into an organized system. It may be an aspect of chronic personality disorder, of drug abuse or a serious condition such as schizophrenia in which the person loses touch with reality.

Sometimes a person will turn to marijuana to reduce their consumption of alcohol. Well, all they are doing is trading one drug for another and it's still an effort to "escape". With that said, there really isn't a way to experience a healthy relationship because the other person is often more interested in pursuing the escape. So often that leads to "the lady in waiting" where you never really get to be part of the person in any real healthy way.

Also, both constant alcohol use or constant use of pot can lead to a person experiencing psychosis. This is a very confused state of mind and eventually has to be addressed as it can get worse with time. It can be a very confused state of mind where the person begins to believe all bad is happening to them and there is not going to be any room for you to experience any kind of "normal" relationship. It sounds like you are trying to make sense out of individuals that have substance problems and you simply can't make sense and any relationship you pursue with a person that has these challenges is not going to be a healthy one. From what you have shared, you are trying to rationalize the irrational. It's a lot of wasted effort and not healthy for you.