At once the simplest and most complex form of relationship is love. Unfortunately, these feelings and responses are very difficult to describe accurately if one has never experienced them, but it is possible to improvise. Fantasy love is not true love, it's prolonged infatuation. It is not actually possible to fall in love at first sight, although people who are infatuated can eventually fall in love given enough time. This is something which should take time to develop, or in some cases, already exist. If you kill off a character's loved one, try to develop the character (the loved one) in your story first, so readers will "feel" the grief and anger that your character feels. However, try to pick up the pace after this with a joke or some other thing which takes the character's (and thus the reader's) mind off the death. This way, you won't depress your readers, and they will actually enjoy the rest of the story.

Other than love, there are (of course) many other kinds of relationships. What does the stableman think of the Master? The Master's son? The kitchen maid? The stable boy? The horse? Strangers? These things do matter, since the stableman will react differently to different people. Be sure to include his and others' reactions to different people in your story.