I have a problem with the fickleness... not the hot-cold thing, which I am guilty of, nor even the push-pull, which I do also. They do more of an instant & long-term obsession, and then they drop you cold once they're over it. Or the opposite - they despise you & then suddenly one day decide you're great. There's no back & forth dynamic that continues indefinitely, it's more like a period of intensity & then it ends...forever. With the sp instinct, you mitigate boredom by creating space here & there, for the sake of your autonomy.
I think an sx/sp would probably suit me fine then, and I've even seriously considered that type as my own. sx/so are more likely to just drop you permanently, and I'm too sensitive for that. I've seen such flakiness in so/sx too, but I still associate the so instinct with wanting to carve out a niche & cultivate something lasting in terms of connection to others.