changes in sex drive after first time sex?

*serious answers only*

so me (F19) and my bf (M19) are in a long distance relationship and we had sex for the first time a few weeks ago, it was an amazing experience but ever since then he recently told me he doesn’t feel the urge to masturbate anymore and he’s not as horny as he used to be anymore, before sex he would masturbate often and when he would ejaculate it was a lot but now after sex he told me it’s not as much.

does anyone know why this happened at all?

is this a normal change after someone’s first time having sex?