I just saw my fiance's penis and it looks like he's half-circumcised. Is that commonly done?

Variety/Spice of Lif. Circumcision is dependent upon the operator and what the operator is operating on. Techniques vary on how to do circumcisions and upon the doctor's choice as to how much skin to remove and upon the anatomy of the penis and the type of circumcision done. Sometimes we just can 't get it the way we intended. Some don't know how to do a proper circ. Depends on how he likes it. Not a beauty contest!
Rarely. It is not very common but there are patients who request a partial circumcision to preserve as much foreskin as possible when surgery is needed for phimosis (scarring of the foreskin). However, the most common reason for this is a poorly performed circumcision where excess foreskin is inadvertantly left behind. This is not of any clinical consequence and is only a cosmetic issue.