There in lies the rub, especially when people change over time and you find you have less in common with them.The question is, how many attributes can you dislike before you can say you dislike the person as a whole? And is that enough that you can also not love the person?
As far as mental health is concerned, these situations may change someone to almost unrecognizable, the decisions some take are to be more supportive and encouraging, while others may walk away.