ok so...
1. The reader knows that the boy is about to break up with his girlfriend, but the girlfriend doesn't know. That is dramatic irony
because Dramatic Irony appears when the readers know something the character does not know. For example, in scary stories, the reader often knows where the bad guy hides, but the character does not. As the character approaches the hiding spot, the readers may experience heightened suspense due to the dramatic irony.
2.Dave's blood pressure medicine game him a heart attack. That is
Situational irony.
Situational Irony happens when something happens that the reader does not expect to happen. For example, if someone robs a thief in a story, that portrays situational irony. Readers would not expect a thief who robs others to be the one who gets robbed.
3. "Oh, great! I'm so glad it's raining, and I forgot my umbrella." That is Verbal irony
Verbal Irony occurs when a character says one thing but means something else. This type of irony is also known as sarcasm. For example, a parent might reveal verbal irony, or sarcasm, by showing up at the door of an extremely messy room and commenting, "I've never seen your room this clean before! You are grounded." Clearly, the parent revealed sarcasm when commenting about the cleanliness of the room.