Is it possible for a man to experience PREMATURE ejaculation due to anal / prostrate play during sexual intercourse?
If your lady "surprises" you by pressing her finger onto your prostrate, YES, you can ejaculate prematurely, and your seman may be more potent, so be sure to "keep a lid on it" or make sure she's on the pill.
Yes, it's absolutely possible (I know for a fact)