Re: Mother in law's boyfriend
No, one should not be oblivious to it and by noticing and forming an opinion on it, the OP has already made it obvious that she is not. However, one should not aggravate the situation either. Realistically, what will the OP's involvement actually accomplish? Given that her mil, knowing what she is risking by behaving this way, continues to see her gentleman friend, it's rather unlikely that the OP's involvement will change this.
Also, if her mil doesn't care what her husband and children (and God for that matter) think of her actions (and her brazen, nonchalant behaviour indicate that she doesn't), why would she care what the OP thinks? If the OP confronts her mil or gets involved in any way, it will only serve to antagonise her mil, which will lead to further discord in the family. Again, the best course of action would be to move out and keep her distance from this situation until it is resolved.
Involvement does make a difference in overall picture, regardless whether it stops her or not.
I know a family that has been destroyed by affair of a married man and married woman. Initially, it did not look serious enough, but people could see something was not right that this woman was frequently visiting this family. Some family friends warned the wife, she instead felt offended by these suggestions. People as usual minded their own business, it escalated, few years later, the two families are completely broken. The wife has separated, kids dont see the parents, what a mess of a beautiful family.
And in west it may not impact her much but in Pakistan, when things will eventually be known to people, she will find it hard to socialize. She will always be "the woman whose MIL had extramarital affair", or "her MIL is a *****".
Its better for her to get out of it now b4 its too late.