You did so well… getting clarity and being willing to see what the person felt they needed. Did you dissociate during that conversation or was it after in the “analysis” phase?
I ask because in what you shared I see consideration: you asked someone else to let her know you’d be walking. I see self-awareness: the walk was your choice, right for you, and you did it! I see strength and we-space awareness: you did share a car ride, and you’ll likely be sharing community. Getting to know someone’s triggers and needs (even if unbalanced) can help map a landscape (and even clear up dynamics and set agreements).
Since I have and can edge towards both anxious and avoidant attachment styles, I can sense the challenge here.
For people with a lot of anxiousness about closeness, they can crave/need “sharing” in all things, WITHOUT FAIL. They can need someone to “never leave me!” and even something that has a whiff of that can feel stark, “You left me.”
I both know that painful internal trigger of… nonsensical abandonment… and also how silly I can feel to have that… and how silly I can think someone else is if we didn’t actually have an agreement to go everywhere together! Like I said, I’m bi- when it comes to attachment styles (which is actually a spectrum).
It’s easier sometimes for me to honor my avoidant style. For example, if my partner/kids might want to stay at a gathering for 6 hours, and I might want to leave after 1 hour… we drive separately and we have that agreement. Or, I’ll agree to come back to get them.
If I know someone’s style is more easily triggered abandonment (and in this case it seems pretty easily triggered – you did not decide to go home with someone else, just walk instead of drive), what is clear is that more upfront communication about options is needed.
I’ve had agreements where any change in venue we will find each other and decide together how to get there. I’ve had agreements where we will check in with each other every 30 minutes or so, see how we’re doing, and if either one wants to leave, we leave together without complaint.
High maintenance. I know, I am. 
I do prefer people be honest about their feelings, and even that they don’t necessarily make sense. Our triggers do not make “sense” but they do hit our senses! Sometimes we end up senseless…
In we-spaces, I know that there are all kinds of expectations that will not get met. People are too different and we’re coming off of global trauma as well. “You hugged me!” “But we always hugged!” “Not anymore!” Yes, crazy making…
That’s where being in improv, and being in calm confidence let’s us have the conversation like you had. HARD conversations. It can let us manage the triggers that make us want to RUN RUN RUN (always primitive brain) and find Right Distance Right Depth as well as finding Agreements that work.
That’s what I’m exploring, best I can. Curious how this feels to you and others, and what refinements might be possible, too. @Cathy does a lot of work on expectations and agreements as well.