Sorry cards... I'm sorry you're not well, we're sorry we can't attend, I'm sorry we had a row..

1. We messed up.  We forgot a birthday, we forgot to turn up to a party, we're sorry but we can't attend their wedding.  We're sorry
2. To put right something we did or said caused them hurt, in a more deliberate way that you regret later. Being sorry & showing that you're sorry means acknowledging you're messed up, and that you do care about the person you're sending it to, and recognise the impact of what you did.  It's important to think about the sort of person you're sending this card to . Think about what message you want to convey and find a card that's appropriate. A blank card to write a message in that's personal may be best for such an occasion. Museum Selection have a lovely range of blank cards appropriate for many occasions)
   
   Saying sorry after a row or similar is a little thing to do - but it can be a very difficult thing to do.  However, it's often the little things in life which can make the biggest difference. Saying sorry is a big step forward to moving in the right direction, & sometimes it's the biggest gift of all, even if it's just to acknowledge the fact that the row happened (even if you feel it wasn't your fault) - and that you want to sit down, put things right and move things forward because they mean a lot to you.  In the grand scheme of things, it's a shame to let one row spoil years of friendship & love.
3. The recipient is going through a rough time, perhaps because they are ill, or have suffered a bereavement, or they've lost their job.  Sending a get well soon card or a sympathy card or thinking of you card similar can be a great comfort to people who are isolated from normal life - it shows that people are thinking of them.
4. They are leaving e.g. a job, a neigbourhood, a charity,  "We're sorry you're leaving" but essentially wishing people well in their new pastures.  A Leaving card could be just the thing you need

There are always two sides to a story, of course, but a good start to putting things right is to acknowledge the importance of the relationship in your life and not to let something like a row or change spoil it long-term. Sending sorry cards can be a good time to acknowledge the importance people have for us in our lives, to send love & best wishes when friends & family are going through difficult times so that they don't feel alone, and to help wtih the sense of belonging, being appreciated that people feel.