Despite the Legends frequently using time travel to change things, they don’t usually undo their own moves unless there were catastrophic repercussions.
Considering what has been released about the next episode combined with how “I Am Legends” ended, however, Legends of Tomorrow might have a way to get out of any fallout from the hookup.
Normally, I would expect that Legends of Tomorrow would carry on with this development and force both characters to deal with the consequences, potentially with a little bit of Nate drama thrown in.