Masturbation problems. Can ruin?

Cousin used to do masturbationon daily basis from last 10 years approx. as per he said... and mean time he is going to marry within 4 months and very scared of disadvantages of masturbation might be make him problematic of his future martial sex life... He just want to know, what are the problems wil raise if one do masturbation on daily basis n that too from 10 years approx. ? Is he perfectly carried out this martial sex life in future with future partner or something can ruin ? What are the common problems wil raise due to daily masturbation (coz he didn't revealed me any problems right now) What are the steps or medical methods to follow to avoid common problems of such addicted things (masturbation) He wil b very thank ful to you if he get the answers to the above questions . Thank you.