Have you shown him that you are not interested in his "support" or is there something you could be doing that is leading him on to think you welcome more? If you are confiding in him about your personal life, he may feel that the right thing to do is help.

On the other hand, if you have given him enough clues that you are not interested, then it's probably time to set boundaries upfront (but with kind words).

So far, it sounds like he means well, but if he starts to have unhealthy reactions to boundaries, then it's time to let him go.