My bf try to control his cumming just before he was abt to come and squeeze his penis very hard, but it didnt help...And he came while sqeezing it and not letting go. In the end he still come...But nothing came out.
I'm not sure what you are trying to say.
But I will try to answer various ways:
1) you can never be 100% sure that there aren't any sperm when a guy comes - even pre-cum lubricant can contain sperm - and yes even that little bit can get you pregnant.
2) holding back won't do him any harm
3) guys can orgasm without ejaculate
did that naswer the question?
When you are saying "cumming" you mean having an orgasm?
Because men can and do have orgasms without any ejaculate coming out.
It's probably best he doesn't do this every time, but it won't do any damage.
I have a friend who doesn't like to get semen everywhere when he masturbates so when he reaches orgasm he holds the foreskin tightly over the end, then goes to clean up in the bathroom.