My bf has been divorced twice, omitted first wife story until 4 months?

my bf is 53, i'm 40. he's been married twice. when we first met he only told me about his second wife, as they have 2 kids together. it wasn't until our 4th month together he told me about wife number one; his exact words were "i'm a bad picker of wives." he tells me both wives were unfaithful to him and that both were also alcoholics. he claims to have put them through treatment, and that he didn't want to give up on the marriages but finally did. he swears he never cheated on them or had a drinking problem. (course, he tends to smoke marijuana quite a bit...) i just wonder how plausible it is that a man can make the same mistake twice. (wife 1 lasted 4 yrs, 2nd wife 11 yrs) why would women cheat on him? he seems really sweet, but maybe he wasn't "there" enough emotionally for him? he is fantastic physically, so i doubt that was the problem. was it lying to me the fact that he didn't tell me about wife number one (no kids with her, though) earlier? should i worry?