You would like to set a boundary or make a decision that you are concerned may not meet needs for another. You have asked them if they are okay with it, and they said yes, but you don't quite trust it. Asking them to "be honest" is likely to be received as an accusation of dishonesty. How can you check in again and get reassurance that they have shared what's true for them?
It may be helpful to remember that there may be a number of reasons someone doesn't share honestly about their response to your idea or decision. They might be judging their own needs as less important. They might feel hopeless that there could be a way for all needs to be met. They might feel fearful of conflict and want to protect harmony and connection. They might be unaware of their own preferences and needs.
Keeping these things in mind you can ask for more honesty in at least two ways. One, you can offer empathy and reassurance and invite more conversation. Here are some examples:
"I want you to know that your needs are important to me and I want to consider them. Would you be willing to share what needs are up for you?"
"I wonder if you are concerned that we will have conflict if you tell me you don't like my idea?"
"In answering me just now I am wondering if you are wanting things to go smoothly?"
"It's okay if you don't like my idea. I have space to brainstorm other ideas so we can both have our needs met."
"I'm confident that we could come up with something that works for both of us. Would you like to consider some other ideas?"
"When I hear your answer just now, I feel curious to understand what's going on for you. Could you share what you are feeling and what's important to you in this situation?"
"When I hear your answer, I feel concerned because I value clarity. Would you be willing to take another moment and see if there is more there for you?"
Two, it's also helpful to play the scenario out and then have the other person answer again. This invites the other person to spend more time with their response and can help bring feelings and needs into awareness. For example, it might sound something like this: "Would you be willing to take a moment and imagine it is the end of the weekend and things have happened as I proposed (share the details of the anticipated experience here) and tell me what comes up for you?"
However you approach asking for more honesty, it's helpful to keep in mind that someone's lack of authentic sharing is not usually about willful dishonesty. It is more often about lack of awareness, inner conflict, or fear of disrupting harmony. Understanding this, you can approach the other with compassion and curiosity which naturally invites more honesty.
Take a moment now to reflect on a situation in which you found out after the fact that someone hadn't shared honestly with you when it would have been helpful. Review the strategies and examples above. What might you have done to ask for more honesty beforehand?