Hold off on the advice
This approach can be challenging, especially when the “right” answer seems obvious to you, or you are being asked directly for it. Resist the temptation! Most people give feedback or look for a solution way too early in the process, and have difficulty leaving things “unresolved” for a little while. So even if you think you know a good solution, resist solving the other’s problem for them. People often just want to vent and see that you get it. Giving advice is rarely appreciated, and certainly not before you have understood the issue from their angle. Instead, show solidarity and encouragement: "We will figure this out together. You’re not alone in this!"
All of the techniques above are highly effective, but they require a lot of skill on your part. The goal is to stay calm, keep listening, and make your partner feel understood. It gets easier with practice!