My bf and I have been together for almost 9 months and just recently I got the implant for birth control because right now I feel like we're both to young for kids. ( him:20 me:19 but will be 20 in a couple months, also neither one of us has had sex). Yesterday we went to try to have sex but he couldn't keep it up long enough to actually do anything and I just wanted to know if it is common and what could cause the failure to keep it up.