I eat only 1 egg at night.
Gotcha. Well, one egg has about 300 mg of Choline from what I remember and that is about what they have in most supplements. But I've never hard of that level of choline making that much difference.
Choline also stimulates the brain and memory. Acetylcholine is important to the brain of course and anticholinergics have been implicated in mild dementia in oder people. So maybe that is your link?
Of course, there are two powerful antioxidants in eggs, lutein and zeaxanthanin, but I have not heard of these improving erections.
Hey, I don't know if you have the money for this, but, if you can afford it and are interested, can you buy a choline supplement and see if it has the same effect? I'm just supercurious if it's the choline that is doing it for you. (And, if you're not int'd, no big deal...)
One caution about choline: it has a very similar structure to carnitine, which may be the "bad boy" in red meat. (Controversial topic I realize...)