Test of friendship
My friend is getting married next week. How do I tell her, without offending her, that I think he is wrong for her?
YOU would need to be very clear about what you think is wrong with your friend's relationship and why you believe her future spouse is not right for her.
It is always dangerous to make judgments about someone else's relationship based on your personal values, tastes and preferences. Relationships often have mysterious glue holding them together.
Even if your reasons are based on an accurate assessment and your motives pure, there is no guarantee your friend will be able to hear you.
If they get married you will be considered to have acted maliciously . If they do not marry it will be because you were right and your friend was able to hear it, in which case she will thank you. You must decide whether you can keep quiet while your friend makes a potentially disastrous decision. - Leonard Carr
I am not sure you can say such a thing without her taking offence. The depth of your friendship will certainly be tested if such a discussion were to take place.
Have you asked your friend what she finds attractive about him and why she wants to spend the rest of her life with him? If you do not agree with her, then this issue is about you, not her.
On what basis do you feel he is wrong ? If you have info about his character, it would be unfair not to share this with her. However, if you are concerned about losing your friendship after she is married, then express that truth rather than blaming him .