Studying too much. Also, watching too much porn between study sessions.
It’s rotting your brain kid, you sound like a smart kid (academically), surely you must know to some extent that the sex from porn performers isn’t indicative of the majority of real life. Or even paid expectations.
Get a girlfriend .... i assure you it’ll teach you a lot about women and yourself .... re sex and otherwise. I almost feel bad for some poor Sp and yourself if you went into your first sexual experience with another person with the intention of cumming in her throat without any warning, just because you’ve seen it in the movies .... it wouldn’t end well and would kill your ego re future sexual experiences for a long long time.
To answer your question if you had a 21 year old virgin gf like yourself and on her first sexual experience you, you tried to cum down her throat without warning ... her in shock gag biting-down reflex or what not would probably end with her unintentionally clamping her teeth down FULL FORcE on your dick. I won’t even get into what she would think of you as a person.
I am sure the female SPs on the board that realize that you’re being serious in your posts are shaking their head. If you see an SP and your new to sex (not comfortable enough of experience enough to go with the flow of things) then make sure to ask boundaries before hand, and always give warning (to civilian partners and SP) before jizzing.