I need help. How does one deal with desperate people?

I have two people that are quite close that are sincerely desperate and I am feeling will say anything to try to get my support. I have helped them quite a bit over the years but now its getting to a point where serious decisions must be made. When someone says that they love you but you know they are desperate how much should you believe them? Like my old manager would say, "We've all got problems.", and, " You can only help someone so much.". Boundaries. It comes down to boundaries. How many stones must I turn to bread? What if the way to help one person hurts someone else? Someone else who says that they love you but does not need help. This all should be obvious to me but it's not.