In relationships, they can be complicated and especially with your family and their family. At first, it is wonderful and you love his/her parents. You try your best to build a good relationship with his/her family. But one day something happens and you've said the wrong thing. This could be to your partner or to their parents. The change doesn't show up right away, but over time, you'll notice a difference. This could be in the way they greet you, talk with you, or even drop by for family get-togethers. By this time you'll realize that they are not the same as before. There seems to be a tension in the room when you are all together, they are short with their answers back to you, or they give you a funny stare when you say something. You also might notice that when you walk in the door and his/her family is there, they will find an excuse to get up and leave. Even if you invite them to say for dinner, they will have a reason to go home or they have other plans.
This is when you know something has changed and you've ruined your relationship with their parents. This will take time to fix and to try and mend these problems. In some families, this is almost impossible.
This is just one example of how you can tell if you've ruined the relationship with your in-laws.
As for your own family, this is a bit easier to tell. You grew up with your parents and understand them. But as you grow older and find your freedom, you change, but they don't. You will start to do your own thing, you'll no longer want to be there for family gatherings, you'll find a reason to skip out or not show up for family dinner. Over time, you'll see a change in your parents. They will start to nag you, they'll keep throwing the facts in your face how you no longer show up for dinner, want to spend time as a family unit, and why do you always have to run out the door to be with this friend or that.
This is the time that you can tell that your relationship has changed with your parents. Instead of asking you if you'll be home for dinner, they will say "see you when you get back". They will no longer plan for you to be at dinner, attend family functions and will go on without you. By this time it is hard and a bit late. You'll start to feel left out when your family walks out the door and doesn't bother to tell you where they are going or even ask you to join them. At this time you'll realize that you've ruined your relationship with your family and now you need to do something to mend these problems. It is never too late. But you will need to realize that it will take time to mend the problems and to have your parent's respect again.