Understanding being "in love" while open

Hi all, I am relatively new to being open. My partner and I (of 10+ years) discussed it together for about 3-4 years before we decided to actually try it with rules and boundaries and an understanding of what trust means for us. For further context, my partner (39, M) does not date - they do not want to and are uninterested even though they have that option available to them if they change their mind. I (35, AFAB femme) am dating women/femmes/NBs separately. I would say apart from a few tough conversations here and there, it has been going much smoother than I thought. We both seem happy and check-in frequently with how the other is doing and feeling/processing.

I've met someone in the last 6 months and started dating them. It's been great AND I am reaching an emotional wall because I am not sure I know what love feels like outside of my current partnership. I enjoy sex, I enjoy flirting, I enjoy chemistry but when it comes to love, I don't know how to trust or feel it that deeply. It takes me such a long time and some of it is that I, at this point, have an understanding of what love is from my current marriage but can't seem to feel what it's like, emotionally, outside of that or feel it on that same level. The person I am dating is looking for more deep love experiences, and I don't want to rob them of this so I am contemplating whether or not I should break away. I recently told them that this is something I am struggling with and we are taking a bit of time to reflect before meeting back up to discuss what we want to do (continue or not continue). I felt relief in telling them, because that does feel like the right thing to do at this point, but I also feel myself missing them.

I don't want to cause more hurt and I don't want to be reckless with someone's emotions and heart. However, I do genuinely enjoy their company and enjoy getting to know them/being intimate. Has anyone experienced this feeling of struggling to feel love outside of your primary partnership (sorry, yeah we are hierarchical at this current juncture), but still knowing you are aligned with a lot of ENM/poly culture and philosophy?

Finally, if you've made it this far, with peace and love I'm asking for some grace please. No one here has this down perfectly and at the end of the day, I'm just a queer bb frog trying to do right and knowing that 1) harm is always possible 2) learning the art of repair is the key to most of our problems. <3<3

[edit]: thanks for the correction on my incorrect use of "solo poly". apologies & heard!