keep at arm's length

verb3

1. •
   Keep at a distance, away from one's body.
2. •
   (figurative) Avoid direct confrontation or struggle.

   • Ramsey's goal secured the points, but the win came on the back of a measured performance that saw Arsenal keep Dortmund at arm's length for long periods and score with a classic counter-attack. — 2013
3. •
   (figurative) Avoid a close relationship.

   • She's been keeping me at arm's length all the time. She doesn't want to get involved.