Hmmm, I am very introverted - yet I've managed to maintain a handful of close friendships with people I've known for many years, decades in some instances. The people I speak of are and have never been lovers, but good, platonic friends. We are not necessarily *always* in touch, but when we do talk, it's like no time has passed and we can discuss anything or nothing, depending on our mood at the time.
Admittedly, due to being so introverted (and lately, pretty agoraphobic), I tend to maintain friendships via online messaging rather than in person or phone calls. Yet this works and because it's "instant", it's actually easier to just launch into a "no particular reason or subject" type of conversation.
Say, I've just watched a great movie, or something political has bugged me - I can just message one of my good online friends and ask for their thoughts, right out of the blue, without there being any obligation on their part to get back to me straight away. My online friends and I often engage in back-and-forth banter and deeper conversation about actual issues in this manner. It's great!
When it comes to "real world" platonic connections of the non-sexual variety - I agree with some of the posters above, who believe it's important not to put ALL one's emotional eggs in one basket.
For one thing, if your romantic partner is your ONLY source of emotional connection, you risk overloading them with your every feeling, problem, issue (mundane or otherwise), over time. Moreover, you only ever get ONE outside perspective on whatever-it-is you wish to receive feedback or advice about. It's good to at least have the opportunity to glean a variety of perspectives on issues that are discussion-worthy, I find.
In this regard, I have a small but diverse range of real life connections I can discuss deeper issues with, including: both my partners, my ex-husband, my two grown children and my daughter's best friend, my brother and sister, two or three old friends who I've known since school days, and a couple of friends I've made and managed to keep since having my children.
But in general, it's usually my partners, my daughter (who lives with me) and/or my closer online friends who I hit up for advice or convo on deeper matters, just because they're almost always available to talk.
I'm not suggesting everyone ought to conduct their relationships and/or friendships in the same vein as I do, though I also don't believe it's necessary to seek out other romantic/sexual relationships simply in order to have other people with whom to share the ups and downs of life. If that is truly the ONLY way (only people) you'll feel comfortable debriefing about life issues with, Rygel, then perhaps you might do some further reading about polyamory to see if this is REALLY what you want/need.
But please, do not go into an additional "romantic" relationship with an agenda that is more suited to platonic friendship needs, unless you are fully invested in having that other person become an intimate romantic/sexual partner. If the close friendship is your sole objective, you'd be better off seeking out better/more compatible friendships. In the same vein, do not be coerced into polyamory because your husband (might have been) already thinking of opening the marriage, and your confession about needing intimate friends was the "excuse" he needed to bring up the subject without feeling guilty. Give it some deep thought and be honest with yourself about your needs.