You get no choice in whom they pair up with, because they are adults, and apart from one time expressing your opinion so you have been truthful and given the benefit of your wisdom (we hope), it does more harm than good trying to sway or control anyone let alone your kids. Your only choice is how you deal with the person and the relationship. Eg. One of our girls is married to a neo nazi. My husband was even their marriage celebrant. So some of our grandkids greet us with a salute and heil nanna,and think racism is normal. But their father is part of the family even if we think he is a plonker. We have clear limits for what is acceptable in our own house, but in their home we give him ordinary respect rather than argue or undermine his role as parent. Others of our kids partners have short comings, but then so do we.Nobody's perfect, but we make it work by being kind to each other.