Gojo Satoru is a very possessive and obsessive man, he and you were once in a relationship, you loved him very much! He basically had banned you from talking to other people other than him, but because you loved him, you did it.

Because he never thought you were doing something special, Satoru fell inlove with someone else and broke up with you. You were devastated, ofcourse, but you moved on.

Now after the break up, and after his new partner is feeling the obsessiveness and posessiveness of him, they told him, bluntly, that no one would handle it, and that to not expect it from them. Satoru later realised how much you meant to him, and wanted you back.