A relationship will work if there is mutual understanding between the partners.
In most of the cases it doesn't work as distances decreases the understanding between them. Partners find it difficult to contact each other. In love, u see ur partner, u hear them, u talk with them and you feel them close to your heart. you feel that they are with you whenever they need you.
in long distance relationships, these things is not present to strengthen your relationship.
It then comes down to the depth of love between then for such a relationship to work.

Regards,
AV