Q: I have a fiancée (Male/Female) in United States, can I go and visit him/her?
A: If a fiancée wants to visit United States to meet his/her Fiancée and then return back to Pakistan then he/she should apply for a visit visa (B1/B2).
Q: I have a fiancée (Male/Female) in United States, can I go and marry her there?
A: Yes, you can however you would need to decide if you want to stay there or come back after you get married.
Q: I have a fiancée (Male/Female) in United States, can I go and marry him/her there and come back?
A: Yes, you should apply for a visit visa (B1/B2) however you have to make the visa officer believe that you are intended to come back after marriage because if you go on visit visa (B1/B2), marry your finacée and do not come back, it will be considered a visa fraud.
Q: I have a fiancée (Male/Female) in United States, can I go and marry him/her there and stay there?
A: Yes, you would be applying for a immigrant visa (k-1) for it. Its recommended and safe so even after marriage you are planning to come back you should apply for an immigrant visa (k-1) because with this visa you can take up residence in United States anytime and there are more chances of you to get it. You fiancée in United States needs to complete the paper work require for K-1 visa and would also need to proof that he/she can support you financially.
Q: I have a fiancée (Male/Female) in United States, should we get married in Pakistan or United States?
A: It depends where you want to get married. In both cases he/she would require to apply for a K-1 visa for you to take up indefinite residence in United States, also, in both cases you would need to apply for a visa in U.S. embassy in Pakistan so the time would remain the same. It completely depends on your choice.
For More details on this, please visit U.S. Embassy Islamabad website