The only reason you keep contact with your ex is because there’s still something there

You’re not “just friends.”

You don’t just “care how they’re doing.”

Or whatever other lies you’re using to justify it to yourself and/or your significant other.

You’re keeping that flame lit, no matter how low it gets, because you’re too scared to let go or you’re easily manipulated or you still hope for something to happen between you and you’re hedging your bets.