Relationships often start on a good tone. However some relationships with time become toxic. The following are signs of a toxic relationship:
1) you feel uncomfortable sharing “good news” as you’re afraid that the other party  will act unfavourably.
2) You can’t express your true emotions or feelings.
3) you experience verbal abuse by way of name calling or insults.
4) you do not trust them and feel that they will hurt you or back-stab you.
http://www.glamour.com/sex-love-life/blogs/smitten/2016/03/toxic-friendship