If Sagittarius lost interest in you, it is because you are too clingy. You should already know that Sagittarius is characterized as a very adventurous, free, social, and curious person. What Sagittarius likes the most is knowing and exploring the world, which is why he hates those people who try to keep him.
He hates all those situations that prevent him from being who he is, and for that reason, he hates all those relationships that overwhelm him and that do not let him do everything he wants to do. And if he sees that the relationship he has with you is one of this type of relationship, he will lose all interest in the relationship and you.
Sagittarius does not want to keep something like this because he knows that it will not make him happy and that, instead of bringing him new things, it will take away energy and the desire to continue.
If you are one of those people who has to control where your partner is and who is constantly sending a message to ask how he is, he will lose all interest he had in you.
Sagittarius wants to live life without limitations. If you do not stop putting limitations to such an extent that you become your maximum limitation, you will not be able to keep their attention. Sagittarius, by your side, wants a person who knows how to respect their space and who does not invade their freedom or privacy. But above all, Sagittarius wants a person who brings him a lot of adventures, experiences, and new knowledge.
You want someone with whom you can learn something new every day and with whom you can share your opinions and ideas without being afraid of being judged.
Keeping Sagittarius interested is easy because it is a person who loves to feel surrounded by people.
But it's up to you to make him feel interested in you or not. If he sees that you are a boring person, that you do not bring him anything new and that on top of that, he tries to control him ... Bad go ...