Simplify the following text for a Grade 7 native English-speaking person.
Original: Monroe and Miller befriended Montand and his wife , actress Simone Signoret , and filming progressed well until Miller was required to travel to Europe on business .
Simplified: Monroe and Miller became friends with Montand and his wife , actress Simone Signoret . The filming went well until Miller was required to travel to Europe on business .