my boyfriend and i have known each other for a little more than 2 years and he's a B-1 business visa holder, which means he can only stay in the US for 3 months at a time. he's visited the US a couple times and will return to the US again in June. we want to get married when he's here in june, but we are worried that his 3 month expiration period will become an issue. i dont want him to leave again after we are married. does anyone have any idea if this is an issue and if he could stay here more than 3 months while we wait on his greencard? will it take 3 months to get his greencard? what if we get married as soon as he gets here in june? and what kind of paperworks do we need to file in order to adjust his status?

someone with knowledge in the area please reply!