I don’t even know how to go about feigning a “congratulations.” I pretty much know the drill … if I don’t support her, I lose a friend. And if I do support her, I’ll feel as if I’m aiding and abetting a really bad decision.
Please also see that “I lose a friend” is not the serious consequence here. Withdrawing means she loses the lifeline you are to her.
So be honest but steadfast: “I won’t B.S. you – you know how I feel. Please also know I want you to be happy, and am here for you when you need me. However, whenever.”
If it helps, in this case, the woman is in her 20s and the man in his 40s. The woman is not mature for her age; rather, if anything, the opposite. Haven’t met the man, but he has never been married and has no kids. The woman believes that if two people really love each other, then what does age or age difference matter? I’m trying to be vague so as to not to flavor the question.
Obviously, staying in or getting out of this relationship is a decision that she needs to make. I’m just hoping for some light-shedding.
And to borrow from my favorite philosopher (Finn in “Adventure Time”): “That road you’re on? Leads to nowhere.” The harder you try to make a case against someone’s choice – especially when that someone isn’t entirely mature – the harder you can expect the pushback to be.
If this 20-something is happy, then embrace that and back off. If this 20-something is not happy, then that’s what you address with her, without using dubious mathematical formulas.