Since Arians fall in love very easily and madly, they decide to commit too early, fight those sudden decisions afterward and try to run away from them, which can last for months. There is often a period when they evaluate their relationships and try to rekindle the spark, during which they become aware of their true feelings and decide on what to do in future.
This indecisive sign has a problem with committing to only one person. When they are in one place, or in one relationship for too long, hey become restless. If you want your relationship with Sagittarius to last, you have to give them space; and you'll probably have to turn a blind eye to their infidelity.
This is one very restless sign. S/he finds it very difficult to be in a relationship more than a few days. S/he likes his/her life to be diverse. They are not overly sexual. It often happens that a person impresses and fascinates him/her, but soon after to lose his/her interest. Stimulate his/her intellect, and you have a big chance to be with him/her for a long time.