This is exactly the sort of dynamic I have with my 2 ISFP lovers. Awesome amazing physical and sensual connection but not enough intellectual stimulation and lifestyle commonality. It's great for whatever amount of time we have together, and if that were to turn into forever great;
How interesting that you had similar experiences with your ISFP lovers! I didn't have language for it at the time, but I remember telling my ex that I'd never had the concept for "sexual intelligence" before I met her. In our case, the sexual connection was so great that we slept together, just for the pleasure of it, a few times after we broke up (not something I ever do otherwise). As for intellectual stimulation - the ISFP in my case was very very smart and had a lot of inner depth, but (now that I think about it given your comment) probably not in a way that could have stimulated me over time. But that wasn't the core of our incompatibility, it was other stuff more in the lifestyle category.
but if I have a soul mate I have a sneaking suspicion he'll be another INFJ. INFJ's are the most NT-like of the NF's and I need someone with a strong thinking function who also appreciates the Feeling point of view. I'm entertaining the theory that I need another Se user to have sexual chemistry; if my analysis of my past lovers is correct all the ones with whom there was significant chemistry are Se users
I wonder if the mutual Se-inferior would have the same effect as Se in another position, especially the Se-Ni combo in the middle of the stack like with ISxPs. Have you ever met another INFJ to whom you were attracted? And/or another Ni-dom/Se-inf (INTJ)?
In my case, there's significant sexual chemistry with my INFP, who doesn't have Se in her stack at all (we don't share any specific functions). But nothing in that specific sexual/sensual realm before or since has compared to the very basic ease and flow of that ISFP experience. And come to think of it, I had another gf once who I'm fairly certain was Se-aux but Ti-dom (ISTP). This was someone I didn't particularly like in some ways even at first, and actually over time grew to despise as a person. But I noticed that no matter how ugly things were at other levels, there was still this completely inexplicable physical/sexual chemistry between us that had no discernible source in how I felt about her. It was so odd ... it lived at the utterly touch-physical level, to the point where I had never even found her particularly visually or other-layer attractive, but there was this basic vibrating physical resonance. I have to say, in that kind of situation, the Se-Ni ISxP combo is kinda scary to me in the effect it can have (and I had no idea what was going on at the time, no language for it). I'm just glad I experienced the beauty of the ISFP sexual/sensual connection as well, so I know the other side of it.
eta:
Weirdly enough, and maybe because I had a particularly bad experience with one, ENFJ is among my least favorite type though they are just one letter off.
I didn't like the one ENFJ I've known, though it wasn't a romantic connection. In my case, I found that I couldn't stand seeing Ni placed in service to Fe. It felt like some sort of weird desecration to me, to place Ni as the servant of Fe as she kept doing (understandably with Fe-dom/Ni-aux).