Hi Jaje79 and welcome
It sounds as though you care deeply for this friend. If you have developed deep feelings and miss having this person so involved in your life, could this be what this is what is spurring you on to want to help him more than you already do by being his friend and listening to him? I speak as a codependent who has traditionally seen her place in life as being a rescuer and this is what I've always felt gave me value to others. The reason I raise this is because my advice to you is that if you wish to help him, the best way to do that is to allow him to help himself if and when he is ready. At the same time, value can be added to a r/s like this by being steadfast and working on ourselves. By remaining as a separate entity with our own lives, we can set the scene if you will, for how a healthy life looks. As the emotionally healthier person in the r/s it's our job to lead by example, and not to enable or lead the horse to water. As we all know, most times that horse won't drink unless it has decided for itself that it is thirsty. I would advise you however to take a good look (if you haven't already) at the basic relationship skills within the Tools menu on the top header, as these are ways in which you can be prepared to aid the communication when he is ready to get back in touch. Being a supportive friend is definitely going to be a positive role to play in his life, but it's important to accept that it will be to a large degree on his terms in that the communication may be broken like this at times and that may not always make sense. You may have read here about radical acceptance?
He may have backed off because he felt the friendship put a strain on his other r/s, or it may be that he felt you were becoming close and this triggered his fear of engulfment if he has BPD traits. Clearly you care very much for this man and it's important to consider your own emotional well being and how you can safeguard this in the process of being his friend. Realistic expectations are vital in a successful BPD r/s. There's a great article which gives a good overview of what it takes to be in a sustainable r/s with a pwBPD and should you have not yet seen this, I do hope it helps you to consider what's involved, so there are no surprises along the way. You can read it
Here.
Keep reading and posting. You're in the right place for support.
Love and light x