In an endothermic reaction, the system absorbs heat energy from its surroundings. This typically means that more energy is required to break the bonds in the reactants than is released when forming the bonds in the products.
Therefore, the correct statement that must be true if a relationship is endothermic is:
More bond energy is absorbed on the reactant side than released on the product side.
This accurately describes the energy dynamics of endothermic reactions.