My western sister married a Muslim man.

Ok, so i need some advice on this topic. My sister from the Netherlands married a Muslim man, he is very strict with Islam. Since they married, we as her family tried to keep contact and slowly getting shut out, we accepted him and tried to keep in mind everything concerning the islam (eating halal, dogs outside) things like that to make him feel comfortable and accepted. But he didn't want my sister to visit us anymore, and slowly we didn't see her anymore. We understood and kept asking to visit but no answer. Now my question is: as a Muslim, if you marry a Muslim both family's are involved right? Both family's realize that when they marry both family's become "one". ? Right?? So how can it be that we as a non Muslim family are not welcome? We don't get invited? We can't see our sister and their kids anymore? Now my sister has a daughter from another man before him, when I saw her she looked very bad, lost a lot of weight, told me she isn't happy and things happen there that isnt good, she learns koran aswell and tells that he uses verses in the koran to keep them there but she knows it isn't what the koran says but my sister believes everything and is in a huge brainwash, make me understand.... and how do I go from this?