You may notice that you want to run away from your twin flame when you have inner resistance towards the connection. You live in denial of how you feel. You feel like feeling the connection is a curse because it haunts you every second of the day. This is the reason why a person decides to avoid the connection. She feels uncomfortable. Running is much easier than confronting how the runner feels.
The latter seeks to have life as he knew it before meeting his twin flame. He doesn't want life to change. This may encourage him to return to old relationships as a refuge. A runner thinks the connection is only temporary and he can go back to his life as it was. But the truth that you meet your twin at a specific time because your soul wants to push you towards this change. And so, you can't stay in the past forever. You have to evolve with the new life situation. You live with the connection every day.
When the presence of your twin flame makes you feel uncomfortable, you want to run away from them. Somehow, he causes all kinds of feelings in you. You are forced to face parts of yourself that you previously thought were unlovable. You feel challenged to rediscover yourself. If you're not ready to face yourself and all your ghosts, running away is much easier.