it's only normal if you've ejaculated or at least in excess.

Literally when u ejaculate you ejaculate all the lover hormones you had built up for her during the sex act and even before that.

Besides that also, ejaculation is by the sympathetic (fight or flight/fear/adrenaline) nervous system. So in a sense ejaculation or ejaculation in extreme (ie fully emptying out) will cause overstimulation of the sympathetic nervous system PLUS being weak and less loving due to depletion of your reserves of hormones.

see, to "charge" up that sexual intoxication you use the parasympathetic nervous system stimulation but to ejaculate you use the sympathetic nervous system.

That's somewhat key to seeing how the Coolidge effect occurs.

It can be worked around though with tantric sexual technique and/or taoist sexual techniques.