Even though twin flame connection is the union of the spirit, soul, body and mind and was sealed by the Universe. No matter what the twins are doing or where the twins are heading to, they are always connected. But it does not mean that twins have to stay with each other or are not allowed to have relationship with others outside of twin flame union. In fact, both are allowed to have space to learn with other people and have other relationships that facilitate their spiritual growth.
When you understand that relationships with others outside of twin flame union are the catalysts that help your twin grow, you will become more relaxed and void of jealousy or the need to blame your twin for choosing others over you. Love is to let others have their own experience and their own choices even though their choices do not include you. In this case, the best thing to do is to turn within and focus on yourself rather than asking why your twin chooses others. Sometimes the relationships with others are the ways for them to learn what they need to learn and prepare them for the reunion later on. Without the experience, they might not realize their connection with you and the connection with the Universe.
Yes, most twins are planned to be reunited at the later stage of their connection but it takes time, patience and a lot of hard work. So instead of blaming your twin for choosing others, pay attention to the emotions that his/her actions have brought you, those emotions indicate some hidden issues needing to be addressed. And you might learn to be happy without relying on others. It is because we have to own our emotions and be responsible for our happiness and unhappiness regardless how others are acting.
Some others choose to have relationships while waiting for their reunion with their twins. This does not mean that you have betrayed your twins. It simply means that you have chosen to learn lessons with others priority to the reunion. Trust that after completing your lessons, the energy in your past relationships will get dissolved and you have completed your soul contract with the other people.
Relationships outside twin flame union are common. This is the evidence of the Universe letting souls to have free will and to learn lessons outside twin flame union. While the Universe allows our twins to learn and to choose others over us, so should we?