What I noticed about your post is that
1. You hone in on one person obsessively.
2. You overshare too soon, as though this person is being viewed as a therapist or maternal figure.
3. When the person blatantly but politely expresses they are not interested, you continue to persist, as though you are a glutton for being rejected.
4. Then you obsess about it more and feel very depressed about it.

All of this is a matter of attachment/bonding issues, which is more so in the realm of psychology than psychiatry.

However I do believe that tackling mood disorder symptoms first with proper medication can make it much easier to then try to tackle psychological problems.