You are so right - if you try and pour from an empty jug, you can try as hard as you can, but you will still pour out nothing. That jug needs to be replenished on a regular basis. What I am saying is that if you just give and give, you get to a point where you have nothing to give to anyone, and you are just bone tired.
Of course you don't give so that you can receive back, but in any relationship, it is important to have a balance of giving and taking. It sounds like in your relationship there is no balance.
We all have our problems - that is the nature of life. If your partner really believes that his problems are bigger than yours, I would say he sounds quite selfish.
When you are in a relationship, you develop a pattern which is like a dance - you do this, then I do that, then you do this, then I do that, and as long as we both hear the same music, we dance the same steps.
You have every right to change the music, which means the dance will also change.
There are different ways in which you can change this situation.
Of course you could talk to your partner and explain that you also need support, and that from your point of view, your problems are as big for you as his problems are for him.
If that does not work, then the next option is to simply insist on time out so that you can do things (without him) that will give you your sparkle back. You can get a creative hobby like painting or gardening or anything that you can do without him (with or without other people) that will re-energize you.
You may be in a relationship where your partner will become even more demanding if you claim time away from him. If that is the case, you will get to a point where you ask yourself what you gain from staying in the relationship.
Another option is to write a diary, and make sure you keep it private, so that you can write whatever you want. It is best to write this when you wake up in the morning, or just before you go to sleep. However, if that will cause privacy issues, then find any other time during the day when you know you will be alone for about 10 minutes without interruption. Then write in that diary. Make sure you use a stopwatch or timer so that you don't exceed the limit of 10 minutes. At the end of the 10 minutes you stop writing and hide your diary away until the next day - even if it is in the middle of a sentence.
What do you write? Write whatever comes to your mind. Don't get stuck in stuff like shopping lists or what you did for the day. Write down your thoughts. Make sure that nobody else - not even your best friend - knows about this. When you write a diary like this, your diary becomes a kind of therapist which helps you to get rid of those thoughts that crowd your mind. You get a different perspective on your own issues, which is more than your partner can offer.
You also need to recognize that grief takes a physical toll on your body. Writing the diary will provide relief for that as well.
You will discover that over time you get solutions for your own issues, and the energy and strength to encourage your partner to use his own energy rather than tap into yours to deal with his own problems. He is a grown man and it is time for him to grow up emotionally as well and stand on his own legs.
And if you can do it at all, disappear for a day and book yourself into a spa. It will be worth all the money you spend on being pampered - and let him worry about where you are - it may make him realize how much you mean to him.
Love and Light