1. He writes whinning poetry: He admits his poetry is full of "whining" and complaining, focusing on his own grief and pain. This type of self-absorbed poetry is seen as foolish, especially in the context of the time when poetry was expected to be uplifting and didactic.
2. He loves a woman who doesn't love him back: The speaker is infatuated with a woman who doesn't reciprocate his feelings. He calls himself a fool for being so blindly in love with someone who doesn't love him back. This is a classic theme of romantic poetry, but it can also be seen as a foolish obsession.
3. He tries to reason with his love: He acknowledges the futility of trying to reason with his love. He knows that his love is irrational, but he continues to plead with her, hoping to change her mind. This act of trying to force someone to love him is considered foolish and ultimately futile.
So, the second reason the speaker considers himself a fool is for loving a woman who doesn't love him back.