BBC - Arsenal promised Perisic that they would sign him, prompting his strong demand to leave Inter
At the end of the January transfer window, roughly 7-10 days, it was all about Perisic and Arsenal. In the end, the club from London just could not provide an adequate offer to meet the demand of Inter.
According to David Ornstein of the BBC, the Gunners made a promise to Perisic that they would do everything possible to acquire him but they also made it clear that they could only act on the basis of a loan deal. This whole thing prompted Perisic to strongly ask to be sold, leaving very limited options for Spalletti for a couple of matches and only returning to the team once the window ended.