The winger discussed the striker replacing him as the Poland captain and his "hurt" at the decision, as well as insisting he has moved on from his clash with Rafinha
The striker has been heavily linked to follow in Mario Gotze's footsteps and swap Sinal Iduna Park for Pep Guardiola's Allianz Arena, although BVB are believed to be keen to hold on to the Poland international.
His midfield compatriot says that Lewandowski is free to follow his own path and insists that there is no bad blood between the pair after Dortmund's top goalscorer this season replaced him as the permanent Polish skipper.
"Yes [I'd forgive him for joining Bayern], but that is his decision alone to make, Kuba told Bild on Friday. "Everyone is responsible for his own career and that is why I don't disagree with people's decisions.
"To deduce that there is a problem with me and Robert [over the captain swap] is a joke. It's normal that he is wearing the armband, right? I was hurt but Robert has the second most caps behind me."
Kuba also inissted that he has moved on from the incident between himself and Rafinha in last weekend's 1-1 draw against Bayern, when he was elbowed by the Brazilian defender then poked a finger in the face of the Schwarzgelben star after being given his marching orders.
"Honestly, I'm not interested. I'm finished with the topic," he continued. "At 27 years old I never thought I could remain so calm.
"It wasn't easy but I made sure I did. I got a call from him [to apologise] afterwards, I didn't expect that. That's just football and you have to accept it."
Bayern have already won this season's Bundesliga title and face Dortmund at Wembley on May 25 for the Champions League trophy.