This sounds like "it causes me anxiety and depression to not do things for other people." That is a very interesting problem to have, I would say. Maybe it is tied to your upbringing. What about volunteering or in some way giving back to the community? It's not romantic, necessary, but it might help with some of that?

I volunteer for a cause that I'm very passionate about, through two different non-profits and a support group in addition to several online communities I help moderate. Yes, I derive a lot of pleasure from helping people, but my 'platonic altruism' needs are being met. Romance, in the cutesy, LTR way is essentially an instinct. I could squash this part of myself, I'm fairly confident I could do it rather quickly too, but I'm almost 100% certain it would never return.

Why can't you have, say, six male friends with whom you fish, kayak, go to bars, and so on

I'm trying to cultivate that, but it's harder than it sounds. My best friend since 8th grade is becoming a shut in after living in a frat house for 2 years, now he goes to class, plays video games, and other than when I invite him somewhere, or drag him out somewhere, he doesn't really socialize, or even leave the house. He has lost a lot of the adventure we had in high school. Most of my friends from school (Male and female) aren't around in the summer, for various reasons, and like I'm saying, they've all got bits and pieces of a very core part of my identity. I don't think a healthy relationship requires a perfect overlap of interests/values, but I feel a really base desire for a relationship that goes farther, deeper than platonic 'Oh you're pretty neat to hang out with sometimes, when I'm free, bored or otherwise not busy.'