let me explain: whenever you engage in such conversations, with your in-laws families, it is very very easy for it to become something massive. in bengali there's a proverb: "jonaki poka theke agun laglo" (fireflies spread this massive wild fire). i absolutely do not want to have rumour spread about my SO in my extended family. i absolutely do not care about what society thinks of me and us, but if we can maintain a good image, where is the harm.
Religion. I'm not religious, but I've absolutely no problem if my SO practices her religion diligently; I might even take part in her religious activities if she wants. But major life decisions must not depend upon religious connotations.
e.g. if she's a conservative catholic, she won't abort the baby, even if her life is on the line. if she's a jehova's witness, she won't accept blood from outside, even in a life-threatening situation. if she's a kattar hindu, she trash talks people from islam. These mustn't be the case at all.
she should be best friends with me (i know this takes time, and i'm more than willing to invest my time and energy here). she should be able to tell me anything, without a shadow of doubt, about anything, without ever fearing about judgements. i should be able to do the same. there should be trust, without an iota of doubt in the mind.
if one of us has taken a decision to do something, without informing the other, the other person should be patient and understanding enough to understand ki, "yaar agar isne bina puche ye decision liya hai abhi k liye, then mera naa janna hi sahi hai, abhi k liye. kuch sochkr e liya hoga. aage jaake toh batayega hi"
political views should be something around the center. not too right, not too left. both have good and bad sides, so it'll be great to listen to both of them views and jo sahi lage jis situation pe, usko apnay. and patient enough to understand a different perspective to a certain problem/situation.