When you aren’t feeling it, when you start tuning out, is when you really ought to be listening, tuning in. Listening to understand the other person, listening to connect to them.
If you are tuning out, then there is probably something going on between you that needs to be rectified. It’s time to really listen. “What is going on for you?”
In other words, no tuning out, ignoring, disengaging, refusing to acknowledge. No stonewalling or silent treatments. These end up bringing distance. Not only from conversation. But worse, you are distancing emotionally. Not only will you have the original problem, you have just exasperated it with this distancing disposition.