My partners habits

My boyfriend is a drinker and a weed smoker. Im 27 and he is 41. I have never dealt with excessive drinking with someone I care for. He has said he needs to stop and he wants to change his life and not drink so much. He has 2 kids ages 13 and 20. When he drinks he becomes very defensive about us being so different. I am too goofy and I wont understand life bc he has kids and i dont. It feels as if he wants to break up bc of these things. I am willing to be there for him no matter he needs and I just dont know what to do. I cannot talk to my friends or family... Can anyone help?