Leave him alone for right now. Regardless of what the diagnosis is for your boyfriend, the timing is too important to ignore. Whether we blame this on his illness, insecurity, nerves, lack of self-confidence, or simply inappropriate behavior your boyfriend sabotaged the relationship as it was on the brink of blossoming. As I see it your boyfriend didn’t break up with you during his episode as much as his episode came during the greatest intimacy of your relationship. He asks permission to marry you, then announces he is feeling suicidal when walking into your parent’s home. You seeing this as selfish is an honest reaction, but it isn’t so much selfish as it is interesting timing, which I think is what you are reacting to.
Based on the timing alone I’d say he was having great difficulty in tolerating good things happening in his life with you. This would explain why he moved toward greater intimacy and once it became imminent he found a way to bail. Also, he didn’t take you up on the offer to go home because (my guess) he was determined (at least unconsciously) to sabotage it. Hence the drinking episode and impossible demand for you to follow through on.
This isn’t something you can fix or couple therapy can help. Your ex-boyfriend has some major issues in his life that need to be dealt with personally and professionally. They aren’t going to improve with your love and support if they can’t be taken in. As much as these things are necessary for all types of recovery a person must be able to receive them. If he is hell-bent on sabotaging your best efforts at supporting him and greater intimacy—you’ll want to give him a great deal of space—and work on nurturing yourself for now.
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