Would anyone know why i can't cum when i am having sex with someone BUT when i'm masturbating (that word sounds pretty funny) on my own i can cum also for those in the US and other countries the legal age for sex here is 16.
You may have developed a "death grip" when masturbating and the pressure you get from masturbating just can't be replicated from vaginal, anal or oral sex. If that is the case you need to back off from masturbating for a while. The other cause may be nerves. If you're doing random hook-ups with people you aren't fully comfortable with, as opposed to one sexual partner who you can get comfortable and relaxed with, then you may have performance anxiety.
I've only ever had sex with one person (friend with benefits) and i trust that person with my life and he is the only one so far who i'm comfortable in having sex with so i'll try not masturbating for 2-3 weeks
