Well, I have found, you want to ruin your relationship with a female, quickest, most reliable way to do it:
Tell her the honest truth about something, you know she doesn’t want to hear.
Doesn’t matter how long the relationship has gone on, or anything else.. You tell them a truth about something, the honest truth about something, that doesn’t agree with what they want it to be, and its just a matter of time before its over.
Women call what you are describing “speaking from the heart”. Don’t try it on them. It always ends badly.
Same holds true for a leftist friend. Tell them the truth about something that disagrees with their opinion and you have lost a friend. But, it is so worth it.