The other expert made excellent points. It is hard to help someone if they will not help themselves. It is a frequent occurrence and can be frustrating and difficult to cope with.
When someone will not help themselves, that leaves loved ones to find a way to cope with their behavior and try to help them in an indirect way. If you feel your boyfriend is clinically depressed, you can start with learning more about depression. This will provide you with answers when he acts the way he does and help you help him. Here are some resources to help you get started:
You can get ideas and support on how to help him from NAMI, which is the National Alliance for Mental Health. They offer numerous resources to assist those with a mental illness and those trying to help.
Support groups are another option. You can join one for family members and loved ones. Through the group, you may learn more about how family and friends have tried to help their loved ones get help. Here is a link to help:
It may be that when your boyfriend sees you getting support and working towards a solution, he may be willing to try as well. You can always ask him to join in or ask his opinion. It may be enough to get him engaged.
I know it's hard to deal with your boyfriend's behavior. Trying to find ways to respond, keeping the relationship going and helping him can take a toll and you can get wrapped up in all the tension and stress. Be sure to care for yourself and take breaks as needed. Take time each day if you can or at least each week and get out of the situation. Go out with friends, talk to people who are supportive and if you feel you want to, try therapy for yourself. It can give you much needed stress relief.
I hope this has helped,