I'm 18,i have a girlfriend the first i really love and i have had sex 2 times before but casual and i was a little drunk both times ,anyways sometimes when i kiss with her everything is normal but after 10 minutes of kissing i lose my erection,i really do love her and we talked about it she says there is no rush but it's frustrating never the less,also after kissing i can see my underwear have little spots of sperm,dots no bigger then 4-5 cm I'm not sure if anxiety is the only problem,and i did actually notice that i have stable erection until i start feeling that my boxers are a bit wet it's not a hole amount of sperm i usually leave after masturbating ... and I'm not frequent with masturbation some weeks i do it 4-5 times some 2-3 .. can anybody give me some advice what to try?