It matters, it is necessary, and it is a poor predictor of anything long-term. All three are true at once, which is why this question is genuinely hard.
Three different things called chemistry
People use the word for at least three separate experiences, and they behave very differently over time.
Physical attraction. Needs to be present and needs to be able to grow. It does not need to be overwhelming at first meeting.
Conversational ease. Talking without effort. This is a decent signal, though it can also just mean you are both socially skilled.
Intensity. The charge. Thinking about them constantly, the feeling that something significant is happening. This is the one people mean when they say they need chemistry, and it is the least reliable of the three.
What intensity often actually is
This is uncomfortable and worth saying: strong early intensity is frequently a response to inconsistency rather than to the person.
Unpredictable reward produces intense focus. It is one of the most reliable findings in behavioural psychology and it applies to people. Someone who is warm then distant, available then not, generates a great deal of what feels like chemistry — and what is actually being felt is uncertainty.
Meanwhile someone consistent, available and straightforward produces calm, and calm at first meeting is very easy to read as “no spark”.
If your history is a series of intense relationships with people who were hard to pin down, this is worth taking seriously. The pattern is common and it is not a character flaw — but it means your chemistry signal is measuring something other than what you want it to measure.
The practical rule
Roughly: chemistry is a veto, not a selector.
Its absence is a legitimate reason not to continue. Its presence is not a reason to override everything else. A great many unhappy marriages had excellent chemistry at the beginning; it is not protective.
The second rule: give it three or four meetings before you decide it is absent. Attraction that grows is extremely common, particularly for people who are anxious on first dates. Attraction that was overwhelming and then evaporated is also common. The first is a better basis for a marriage than the second.
Where this shows up in Jewish dating
Two versions of the same mistake, at opposite ends.
Where dating is structured and fast, there is sometimes pressure to decide on compatibility alone and treat attraction as something that will arrive later. Sometimes it does. Sometimes people marry into a lifetime of quietly hoping, and that is a heavy thing to carry.
Where dating is less structured, the opposite: a long run of intense, short relationships with people who were never going to build anything, and a set of genuinely suitable people rejected as boring.
Both are errors of weighting.
A more useful question
Instead of asking whether you feel chemistry, ask: do I want to touch them, and do I look forward to seeing them?
Both of those are more stable than intensity and both are more predictive. If both are yes and steady, you have enough. If either is a consistent no after several meetings, that is real and you should not talk yourself out of it — no amount of compatibility fixes it.
If chemistry keeps winning in practice while you say other things matter more, the Dating Priorities tool is worth eight minutes. It makes you narrow twelve traits to three, and the gap between what people choose and how they actually date is where most of the insight is.