Maksim Chmerkovskiy apologized to his "Dancing with the Stars" celebrity partner, Vanessa Lachey, in a tweet Wednesday for his absence this week.
"As you are all aware, I had to leave the show last week to take care of some personal issues. I take full responsibility for my absence...." Chmerkovskiy wrote to his 664,000 followers.
".... and want to apologize to my partner Vanessa. We are both looking forward to dancing for our fans next week!" he added.
Alan Bersten filled in as Lachey's partner as Chmerkovskiy dealt with his "personal issue" Monday.
"There's a big chemistry issue," a source told People. "They both have big personalities and that's not always the best recipe for a good partnership."
"They've been fighting a lot," the insider added.
Chmerkovskiy shared similar sentiments on Twitter the same day.
New week! VEEEEERY excited for @DancingABC new dance studio and new dance with @VanessaLachey! Can't wait to be back in the Ballroom!" he wrote.