I take too long to finish.

[jenlai29]

If she's a WL that's worth her salt, she's more likely to be disappointed in herself than not liking you for losing your erection. It's her job to satisfy and pleasure you during the session. If you don't get that, she will likely lose a return customer. Don't think too much about this.
This also applies to GFs and wives, btw. Men always think women dislike them for lack of performance, but the main effect on the girls is they start second guessing themselves not the men: Am I not attractive enough for him? Not sexy enough? Something wrong with my pussy? And so on.

Back to your problem. Like other bros said there are a lot of factors at play, but since you're only 23 it takes out a lot of those related to health. So I think it could be libido. Do you actually not feel horny when you go for a punt?

You also need to understand what you personally like during sex. Then you take control of what happens in the session and make sure what ever you like happens. For example, I personally like to "service" the girl more than receiving it. So I always try to take charge and tell the girl to lie down at the beginning of the session. Some experienced girls like to stick to their routines and refuse to let me service them. I always perform poorly in those sessions.
That's just my example. You could be someone who likes to be serviced so you have to ask yourself what you really like and go for it.

That's a very interesting point that I've never tnought about. Now I think back to it a lot of the WLs I've been with mostly puts my pleasure first when working.

I may not have enough libido at the moment when I go for a punt. I've been abstaining away from it (incl. masturbation) though today I really wanted to go for a punt but chose not to. But I think I should crave it even more before I go for my next punt.

Another possible factor is when I change girls its more of a feeling for each others rhythm and learning how each other work. I do prefer girls that I've built rapport on. I find it more satisfying. Since I've only started going to FS places recently, maybe that's the reason why; I'm not comfortable with the girl I'm with yet.

An example of this is one of the regular WLs I go to at 42G has changed her routine to suit me and the last time I saw her, she helped me out with her hands then let me finish inside her. I thought that was a really good tactic by her. I'm really keen on seeing her again soon though, but I'm always intrigued on seeing other girls on their roster.