You state that it was worth mentioning the guy was much bigger than you?

Why was this the case for you? Could this be playing into it? It may have happened regardless the size or situation. Sometime your cock has a different mind of their own. Sometimes a brief thought sets a spiral of descent that sends the cock to a limp state. Much of it is all in the wrong head 🤣. The one on top fucks with the lower one. Sometimes it may be that it’s too much of a mental stimulation. It happens more than you may think.

At any rate, do NOT let this start a mental fuck where now any cock even, even a few millimeters bigger than you in any de mention, makes you go limp. Remember that variety is the spice of life. Enjoy the experiences for both you and her. If you need to get over the hump, take a pill to assist you in getting hard. Wishing you all the best.

Use an Ed pill like viagra or whatever. Get a stronger one too. That shit will stay hard. You don't want a performance issue to happen when it's time to shine. Like has been mentioned your mind fucks with your cock and the slightest odd thought can shrink you up quick. So use the pills so you don't have that issue