My personal experience:
I started dating my boyfriend when I was really into the MBTI, and at first I thought he was an EN, like me. A while later I came to the realization that he is actually a very strong S. I'm anxious in general and I'm very, very serious about relationships, and this development scared me. I worried we wouldn't be able to connect deeply enough. It was about 6 months into our relationship, I think, and I was already feeling some trepidation about me wanting to get super "deep" and not feeling that with him.
So I wrote about it on here... predictably, some people told me how awful I was for voicing it. Others, both S and N, were patient and compassionate, and advised me. This was the comment most helpful to me:
Crescent Fresh said:
I think you're right (on bolded text) that everyone has this side of them, though it's relatively easier for NFs to explore this. It might takes some time and effort to elicit SJs on the same mental plane as yours.
Though isn't that the fun aspect of this union? I thought love is supposed to be challenging (and sometimes struggles) and it's all part of learning process. You don't have to lower your expectation on spirituality from him, though you can lessen your expectation by guiding and taking him to the this level gradually. What's more important is that perhaps he'll teach you how to be more grounded and focus on the practial side and appreciate to cherish the present intimacy?
What I'm trying to say is, usually it takes endless patience to discover that subtle connection. I think most NFs come out strongly in the beginning when they're involved in a new relationship through idealization; whereas SJs tend to grow stronger as they have a more grounded approach in romance. Just try to expect less from him at this moment, so that there will be an opportunity for him to surprise you!
Maybe he didn't express his depth of soul because he is learning this from you and wasn't able to express it accordingly. Somehow I think it is important to consider that the principle of diverse love is to recognize you are not the only individual in the cosmos, that all around you are other individuals, other souls, other Human beings, have different perception of the spiritual world. They are different from you and not you, yet you must communicate with them and understand them. Once you conquered it, that's when love become much more meaningful and precious.
Two years later... I can report this much: S and N are two different ways of interpreting information. Ss see data points; Ns see data bridges. This causes Ss to be more drawn to discussion of the facts (better yet, just the facts themselves) and Ns to be more drawn to discussion of the relationships between facts, but what it does not impact is the
content of the data, if that makes sense. S and N preferences tell you only how people like to take things in, when given the choice, but nothing beyond that. My ISFJ is better at philosophy than I am... he is more into politics... he has read much more classic literature... in my opinion he is smarter than me in many ways. So, as for superficiality, that is not at all true. You just have to understand that an S generally wants the facts for themselves, pure and raw, to chew on in their own mind, which is why they will not be so interested in three-times-removed abstract analysis. Which in some ways is really deeper than N processing - it's closer to the source.
As for the element of more "spiritual" depth... this one was harder for me to understand. Again keep in mind that S and N describe how we frame things. Being NF, you and I, we like to see things in magical cosmic mush. Connection and value fused holistically to create what we perceive as "deepest meaning". We like to revel in a mystical feeling of interconnection with the known and unknown. And that's where we feel most in touch with life and significance. But when you break it down... you are getting those feelings because you are looking
at something in your mind... and those feelings are your personal response to that data. The thing is... another person of any type can easily value looking at the same things you do, but they might not enjoy that same response so much. They might respond differently.
What I mean in application is that I used to be so worried that my S might not connect with me like I wanted. But it's kind of funny/sad, he wasn't connecting with me like I wanted because I wasn't understanding that he was appreciating the same things as me, but taking it in, responding, and expressing that in a different way. At the heart, we care about the same things, and I have had to learn to open myself to see it through his eyes. To me, going through historical data makes me snooze. To him, it lets him revel in visions of the past and to feel the echo of thousands of beings having been here and lived here and loved here before. In that case he's much more deep than I am! What is most important to me for our relationship is that we share the same values, and we do. He just happens to be much more realistic and practical about them, lol.
IMO, instinct variant is the same. It's all about the framework and not about the content. I thought I was sx-first because I always wanted depth - I was wrong, though. I find more depth in long, constant-contact, strong bonds than in super-intimate, super-high-intensity sx connections. It's all about where you find the depth... everyone has it. I totally admit that I once thought otherwise and I am somewhat embarrassed but very happy to say I was self-centered and totally wrong.
So in your case... given your ISFP... there is still SO much to know! His values, his interests, his projects, his beliefs, and so on. The CONTENT is the same as for an N. But you might have to open your own mind and try to adjust to his way of communicating, because you might have a harder time understanding/seeing the depth if he's not communicating in N terms. What my experience taught me is it's not a deficiency on the S end... it's a deficiency on the N end. Or, better yet, it's just a difference, but if you're the one desiring connection, you're the one who has to be willing to reconsider that your way of looking at things isn't necessarily the only meaningful way. The easiest route, IMO, is the direct route: ask him what he finds interesting. He might enjoy existentialism, who knows. If you want him to open up and respond... ask him what he likes and engage with him about that. You'll find plenty of depth there.