Barca and Bayern confirmed on Friday that an agreement is in place for Coutinho to move to the Bundesliga champions for the 2019-20 campaign – the deal including an option to buy the playmaker.
Coutinho had been linked to Paris Saint-Germain as a makeweight in a possible deal for former Barca star Neymar, however, the Brazilian is now set for Munich after watching Friday's shock 1-0 loss at Athletic Bilbao from the stands.
Asked about Coutinho following Barca's disappointing LaLiga opener, head coach Valverde told Movistar: "It is a situation that last season when the league ended the player had it in his head.
"This has come up, he has accepted and hopefully he is lucky."
Coutinho, who will help to replace James Rodriguez after his two-year loan from Real Madrid ended, has struggled to cement his place at Camp Nou since joining Barca in a reported €160million transfer from Liverpool in January 2018 – a move that saw him become the world's second most expensive player.
The 27-year-old Brazil international scored five league goals as Barca retained their LaLiga crown in 2018-19, while he managed 11 in all competitions.
Coutinho is set to follow another loan signing – Ivan Perisic – through the door, though sections of Bayern's fanbase were not impressed by the deal to sign the Inter forward, who came in as an alternative to Leroy Sane after the Manchester City winger suffered a serious knee injury.