HELP! i dont know how to c.u.m, it just wont come out even im almost there, my bf thinks i dont love him!?

i know its confidential to ask but i have to ask, I'm desperate, i had c.u.m before but i cant remember anymore when was the last time i really did, there are times that i do hhhm play with myself but it just wouldn't come out, is it just because i'm holding it to come out or i just don't know how to c.u.m???, i don't want my bf thinking that i don't love him because of this, geez i sometimes even FAKE MY C.U.M just to believe him that i did had it... its a concern of mine, i need advise and help, pleaseee