HI there Worried Partner1 and congratulations on a beautifully worded and thoughtful post.
Like White Knight and Learn to Fly, who have both made excellent points, I really feel for you and the emotional battle you are fighting so very well.
Just a few suggestions that I hope will help your thoughts:
1. Please look after yourself. You have done a massive amount of work on this situation with empathy and understanding.
2. Try not to feel hopeless but regard this as a test, maybe an opportunity to look back on later and reflect what you may have learnt. They say that adversity strengthens us, but the journey can be rotten at the time.
3. After telling him that you love him and value your relationship, is it time to tell him how his behaviour has impacted you? Be very clear and caring, not judgemental or critical, as you don't want to inflame the situation. But if he understands that you are his 'Rock' and he is hurting you, it may have a positive effect on his thought process.
4. Now this is a tough one. I also wonder when it might be time to ask him if he wants the relationship to continue? He may think he is dropping hints about how he feels but, maybe some closure needs to be applies to this?
I was in a four year relationship which became one sided with the 'love' coming from me. I could sense things were not quite right yet my partner (who was very beautiful) ensured me she was happy. I got pretty miserable and decided to being things to a head and suggested it might be better for her if she moved out. To my surprise she readily agreed - but then asked if she could leave her piano in my house so she could visit and play it. A week later guess what, she started a renewed a relationship with an old flame! So of course the piano had to go and I felt a weight was lifted off my shoulders and emotions.
A couple of years later we met at a party and she admitted she had not been happy for a year or more in our relationship.
The point is, sometimes it is better to go with your instincts, look after you own well being, stop being a bathmat and stand on your principles.
Only you can judge how you feel about doing this as you appear to love your partner and the care you are showing is amazing.
All the very best, hope this helps a little!
Love to hear back from you. The Bro.