1. They fall in love with ideas.
Deep thinkers are obsessed with things that look beautiful and make sense. They are quick to fall in love with the idea of someone, or the idea of love, but then can struggle with the reality of it – the reality that isn’t always logical or coherent or aesthetically appealing.
2. They know that love isn’t enough.
People who think deeply understand that simply loving someone is not enough to sustain a relationship, and therein breeds the problem. They recognize that compatibility is as essential as chemistry, but that it’s not an exact science. This leads them to frequently over-analyze personality traits, patterns and behaviors with an unnecessary amount of neuroticism.
3. They intellectualize their feelings.
People who think deeply get their joy from… thinking deeply. They have a hard time simply feeling something to feel it, or enjoying something without understanding some kind of profound meaning behind it. If they were this way, they wouldn’t have developed their capacity to think so much in the first place. It’s not always natural for them to learn to follow their hearts.
4. To follow their hearts, they have to trust themselves.
And “trusting yourself” is not a simple business. Between your confirmation biases, inability to predict happiness, inherent selfishness, level of denial and so on, people basically spend their lives reaffirming whatever they want to be true. It can psych a deep thinker out to recognize that they can’t always see objectively – especially when intense feelings are involved.
5. They attract parters to fill voids.
Deep thinkers are very often wounded in some way. Those who haven’t gone through any significant degree of pain in their lives usually have no reason to be so analytical or contemplative. A side effect of this is that they attract partners to re-create old relationships, rather than complement them as individuals.
6. They try to shield themselves from potential pain by identifying ways potential partners aren’t quite good enough.
Everybody does this, but someone who is already prone to deep thinking is particularly susceptible to falling into the “nobody is good enough” mindset. They will be quick to point out every single way a person is potentially going to fail them in a relationship, and often unfairly so (nobody is perfect, everybody fails at some point). Of course, this is all in an effort to try to shield themselves from potential pain (which everybody is guilty of, to be fair).
7. They overthink the obvious.
Deep thinkers can often make things unnecessarily complicated, whether that’s overthinking what it means that they were rejected, then internalizing that feeling of unworthiness and letting it control them, or even something as simple as what to say on an online dating profile.
8. They prefer things in theory, not practice.
Deep thinkers exist because they are most in love with the worlds they can create within their minds. When a reality they choose disrupts their fantasies, it can be traumatizing.
9. They fall in love with who a person is more than what they make them feel.
A deep thinker wants a “because.” They love someone because they are aligned on political beliefs and have shared interests and similar future plans, not just because they feel something in their chest when that person walks by. A deep thinker is too keenly aware to misinterpret that attraction for any real level of compatibility. However, this leaves their pool of options smaller than most: they won’t settle.
10. Their standards are naturally higher.
They want someone of substance, someone who will challenge them, inspire them, get along with them, and complement them in really significant ways. Deep thinkers will not settle, which often means that they will go longer than average before finding someone who they can really invest themselves in.
11. They look before they leap.
It’s more common for a deep thinker to have a longer string of almost relationships and would be partners than serious failed relationships, because they are more likely to analyze and evaluate before they really commit. This means, unfortunately, that they don’t always try: a lot of the time in love, you can’t know until you do it, and sometimes, your judgements – however well-thought-out – are just wrong.
12. They are secretly deep feelers – and deep feelers fear love as much as they long for it.
The thing about deep thinkers is that they are sensitive beings – so much so that they protect themselves by creating a persona that appears to intellectualize things more than they’re affected by them emotionally. At the end of the day, deep thinkers are often afraid of how much they feel, and that can leave them very cautious and hesitant when it comes to putting their deepest feelings of all on the line. 
