You sound like nice people -- just perhaps not yet sure
people? That doesn't have to be a bad thing. Being in a Time of Discernment isn't horrible. It's where you figure stuff out.
If I am not satisfied with any other arrangements though and she decides to close everything, I will feel guilty, and worry that she is going to resent me forever.
You might feel bad that you have to tell her "no, not like that." You can even say that.
"I'm sorry. I feel bad I have to tell you this but NO. I do not feel emotionally safe that way. I would not be free of worry if I don't have some assurance you aren't off with a weird stranger. I care for your well being.
So my idea so that you can meet the need for you to date and so I can meet the need for me to feel safe about your dating is for me to meet the person you date.
What is your idea to get both our needs met? To close. I am ok either way and you don't like my idea so we pick yours. You cannot resent me for that being the thing chosen when you do not put forth a better solution to meet both needs. "
You are responsible for your own and your partner's well being -- in mental health, emotional health, physical health and spiritual health. Saying "yes" to conditions where you feel mentally unsafe, emotionally unsafe, physically unsafe or spiritually unsafe for you is careless. Why hit your own head with a frying pan?
All she has to do is a) work on meeting the requirement for your suggestion and she gets to date like she wants , or b) propose some other acceptable to both solution that meets the needs for both.
It is not a crazy thing to ask. A call, an email, a face-to-face meeting... something to help reassure the spouse a bit? How is that evil? It isn't.
If her proposed solution does not ACTUALLY meet her need and she feels resentful of that being the choice chosen?
It's on her to own her resentment. She can't fling her yucky feelings at you. Because she did not meet her OWN need. She has to own her OWN emotional management and not expect you to own it for her or mind reader her.
Slow things down. Talk this stuff out. There is NOTHING wrong with taking your time to educate selves and grow stronger skills.
Going in under-prepared? That's not exactly UPPING the odds of successful polyshipping.
You guys have started with the initial ID of weak points in the monoship -- communication skills, emotional articulation skills, sorting out what kind of open relationship model you would like. But it's just the start.
You are going to a counselor -- perhaps a talk with counselor can help ID other
places that could be strengthened before major life changes are made?
Hang in there.