Should you tell a friend their partner is probably wrong for them if they haven't asked?

Here is the setup: your friend is happy, nothing is dangerous, and you have a hunch the match is wrong. A hunch is all it is. You see a few dinners and some group hangouts. They see the whole thing. Telling them unasked means handing a verdict on a relationship you only half understand. Then look at how it plays out. If you're wrong, you've insulted someone they love, and they'll remember it at every holiday. If you're right, they were probably going to find out anyway, and now they also know you were rooting against them. People rarely thank the friend who called it early. They tend to get defensive and dig in, and the couple gets closer, with you on the outside. Waiting is not the same as lying or going cold. You can stay close, be curious, and ask open questions like how things are going. If your friend has doubts, they'll bring them up, and you'll be the safe person to bring them to, because you never lectured. That trust is worth more than getting the first word in. Honesty matters in friendship. But honesty works best when someone can hear it. Unasked advice on a happy relationship mostly can't be heard. Wait for the opening. If it comes, be straight with them.