Complex sentence: Brook was scheduled to fight in a unification bout against Jessie Vargas, whereas there was negotiations for Golovkin to fight Chris Eubank Jr., however negotiations fell through and Brook agreed to move up two weight divisions to challenge Golovkin.
Split into simpler sentences: Brook was scheduled to fight in a unification bout against Jessie Vargas. However, negotiations fell through and Brook agreed to move up two weight divisions to challenge Golovkin.