What Causes Difficulty In Penetration During Sex?

Hi, may I answer your health queries right now ?

                                                  hi sir

While having sex with my wife, some times my pennis is not going inside (Vagina) so the sperm is coming out. some times i'm getting mood out, whicle doing sex so my pennis is becoming cool. do I have any problem. Please let me know sir. so I can take action accordingly