Aren't we such a nice customer!!

To be honest, you pay your money for you to cum. So technically speaking, as long as your bit is done, it should be "mission accomplished".

But, of course, that's not a fun, really.... we want to see the girl to cum as well because:
1) You feel you achieved something
2) If you are getting along with the girl, it is natural desire for her to have a good time too - it's a natural human feeling

Anyway, thank you very much for all the advise - I'm not so experienced in this field and all the bros technique/suggestion is great!

Another important part is, to make her cum is not everything for a successful part. As long as you treat the girl with respect and have a nice chat before/after the session, it will leave a good impression to her even though she didn't cum.