Hi Deja Vu, welcome
Soft caring words from PamelaR there.
I think you might need some insurance because the possibility of you finding a stable committed partner in this relationship seems to be slipping- hence you reaching out. Your fear is evident and I understand that fear having have 3 long term relationships fold on me all over 7 years long.
I understand you love him and care for him. The issue is, that whether or not it is his depression or other reason for him abandoning ship twice now is immaterial to you in this- he leaves and you are left holding onto - well nothing for months. That is not a good foundation for trust in communication. It doesn't display he cares for you (although he may well do), it doesn't give you hope that if he returns he can give all the reassurances he likes, you will still be in fear it will happen again.
My suggestion is because of the above you are better off mental health wise, to put this relationship aside in your mind and get on with life as a single person even though it is difficult. Meet new friends, have fun, be adventurist and above all..use distractions to the best of your ability all day right up until you are exhausted and need to sleep so you don't start thinking about him. That is your insurance because you have to protect yourself from what is more real and more likely, that it wont work out.
That advice isn't being negative to you, but a safe zone for you as his communication isn't reasonable.
Beyondblue topic the significance of being reasonable
Beyondblue topic REJECTION, it's hard to swallow
Beyondblue topic does stubbornness have a place?
Beyondblue topic festering issues or moving on?
Beyondblue topic Relationship split
All of those are relevant to you. Just read the first post.
I hope that helps. Repost if you feel like it.