Stay close at work but maintain polite distance outside work. That's a true relationship principle.

Build positive colleague relationships: communicate actively, listen carefully; respect differences, avoid conflicts; offer help, share resources; maintain positivity, spread good energy; avoid gossip, keep confidentiality; participate in activities, strengthen bonds; express gratitude promptly, foster cooperation. Interact sincerely and build trust over time.

The best way to keep a good relationship with your colleagues might be to, I think, remain some distance. Everyone needs private space and you have to leave them alone sometimes, for not just colleagues, but even the most intimate friends and spouses.