It is perfectly fine to vent. It is actually healthy and stress-relieving to blow off steam and unload on a close friend. But before you do, you should make it clear that you are just venting and not looking for them to assist with solving your problems. Because they are your problems, and no one else's. It would be unfair of you to demand that someone else solve all of your problems for you, and frankly would call into question your ability to solve your own issues.
Likewise, when someone brings problems to you, it is unfair of them to dump those problems on you like the lost luggage at the airport. Instead of just accepting their problems and thinking it is your place to solve that for them, try to push them to clarify. Ask "Do you need me to help, or are you just venting?" Make it clear that the latter is perfectly OK to you.
If someone is trying to get you to solve all of their problems, then I recommend two things. First, place their problems back on them. Ask leading questions like, "Well, what do you think you should do about this?" or "How can you help solve that problem?" Often, the person knows what action they want to take but just want some affirmation. Second, start to think of it as physical luggage. If you were at an airport (where you are not supposed to leave your bags with others), and random people left their suitcases with you at their leisure, you would not take it, but you would deal with it in a respectful way.
I met a guy on an airplane one time who said that on his return flights, he never picked up his luggage. He would let the airport sort it out. His philosophy was that it was so annoying to deal with waiting on his luggage that he would just call and report his had not yet been delivered, and they would drive it to his house. He would basically dump the whole waiting game and expect someone else to clean up his mess.
Who's mess are you cleaning up? Who's baggage are you storing? Let them start taking care of their own emotional luggage today.
