Originally Posted by JinnKai

Roughly speaking, I'd say sex can take the following paths:

It hurts her too much to continue
It hurts you too much to continue
Your genitals bleed
Her genitals bleed
You get scared
She gets scared
You lose your erection
She loses interest
The condom breaks
She cries
You cry
Parents / roommates walk in
You're too drunk to continue
She's too drunk to continue
It's bad (for non-specific reasons)
It's good
It's great
It's so good you can't speak

That's just a general listing from my brain. Over all, there are 18 possible combinations.

Your first time, they're all roughly the same odds of happening. This gives you 3/18 (1/5) possibility of having a good/great/amazing time. This also unfortunately gives you 15/18 possibility of having a not-so-great time.

Luckily for you, the probability of the first 15 happening decreases proportionally to the number of times you've had sex. So yea, your first time can (and probably will) encounter difficulties, but it'll only get better looking forward. And "looking forward" can be again that same night.