Following will help to understand the vitamins and minerals needed to produce serotonin and GABA.
serotonin pathways.jpg

GABA deficiency or high Glutamate levels is another major cause or pre e.
Vitamin B6, 5-HTP, L-GLUTAMINE, TAURINE are needed to cure it.
gabapathways.jpg

I think a good multivitamin/multi-mineral can be the solution to premature ejaculation and ED problems.

Iron, Calcium, Magnesium, Zinc, B3, B6, Vitamin C all has a pivotal role in premature ejaculation.
Additionally, you can supplement with L-Taurine, L-Glutamine, 5HTP etc.

B6 & B12 increase dopamine and can cause insomnia. Better to take these supplements in the morning.

Note that B3 is created from Tryptophan in the presence of B1, B2 and B6.

For more information, search about "pyroluria" and "histadelia".