Christensen withdrew himself from selection for Saturday’s FA Cup final against Liverpool on the morning of the Wembley clash.
The 26-year-old is understood to be poised to join Barcelona this summer on a free transfer after a decade in west London.
Blues boss Tuchel does not know yet whether Christensen will be available for the last two matches of the season, against Leicester on Thursday and Watford on Sunday.
Tuchel explained Christensen felt unable to play the FA Cup final despite no injury, intimating a note of caution on how the Denmark international’s situation will be viewed.
“I’m not sure yet if he’s involved tomorrow and on the weekend,” said Tuchel.
“Andreas came in the morning of the match to speak to me and tell me that he’s not ready to play the match, not to start or be on the bench.
“He had his reasons, they stay private and confidential. But it was not the first time as you can see over the last weeks that we had some of the same situations.
“That’s why he did not play so regularly in the last times. We thought we were in a good progression and development, but the conversation took place, we had to respect it and we of course respected it.
“It was very short notice now before the cup final, and not only this match, other matches in the other weeks. There’s no chance I have any prediction for tomorrow or the weekend.”
Christensen impressed in Chelsea’s 3-0 Premier League win at Leeds, in the final outing before the FA Cup final.
The Blues then lost the Wembley showdown 6-5 to Liverpool on penalties, with Christensen not involved on the day at all.
Tuchel insisted he will not take Christensen’s situation personally, with the defender still a part of the Chelsea squad.
“We had to accept it and we will accept it,” said Tuchel.
I'm not sure yet if he's involved tomorrow and on the weekend
Thomas Tuchel on Andreas Christensen
“I try the best I can not to take things personally, and I still believe Andreas wanted to play these matches, I still believe he could in terms of potential and ability.
“And he struggled over the last weeks, as you can see, when he was not in the squad or not playing although he was physically available.
“It was not completely out of the blue sky. We thought we had prepared him the best way possible with a very impressive game at Leeds. He is a key player.”
Chelsea have already secured a top-four finish and Champions League football for next season, but can rubber-stamp third place by beating Leicester at Stamford Bridge on Thursday.
Timo Werner, Mateo Kovacic and Callum Hudson-Odoi will all miss out, with Tuchel potentially rotating resources after Saturday’s punishing extra-time cup final.
Kai Havertz faces a late fitness test on his hamstring problem.
Chelsea have lifted both the European Super Cup and Club World Cup this term, and wound up losing the League Cup and FA Cup finals to Liverpool on penalties.
Tuchel admitted those final defeats have left him wary of making a judgement on the campaign.
“I refuse to judge the season by just penalty shoot-outs,” said Tuchel.
“If we had won two penalty shoot-outs it would have been one of the most successful seasons you could play, with four titles.
“But we are the first to admit it’s not the same to play a final and to win a final.”
Chelsea will face Mexico’s Club America, Charlotte FC and Arsenal on this summer’s USA tour.
The Blues will take on Club America in Las Vegas on July 16, Charlotte FC in Charlotte on July 20 and Arsenal in Orlando on July 23.
“We’ve always had a lot of success on our US tours,” Chelsea technical director Petr Cech told the club’s official website.
“We have a huge fanbase in the US that we’ve proudly built and we’ve seen that getting bigger and bigger every year.”