You will not know for certain, and waiting to is the actual problem. Nobody gets certainty. People who describe having been certain are almost always describing a feeling they had, not information they possessed.
What you can do is check whether the things that predict a good marriage are present.
What actually predicts it
You can disagree and come back. The single most useful signal available to you. Not whether you argue — whether you repair. Couples who fight and reconnect are in better shape than couples who never fight because one has stopped raising things.
You like who you are around them. Not who they are. Who you become. If you are more patient, more honest, less performing, that matters enormously. If you are more anxious, smaller, or constantly managing how you come across, that matters just as much in the other direction.
You want the same life. Concretely: children, where you live, what your home is Jewishly, how close family sits, what work means. Not compatible personalities in the abstract — the same actual life.
You can tell them something difficult. Have you actually done it? Not hypothetically. If the answer is no, you do not yet know whether this relationship can hold the truth, and a marriage will need it to.
You respect them. Attraction fades and returns. Respect, once it goes, tends not to come back. If there is already something you find slightly contemptible, take it seriously now.
They do what they say. Unromantic and extremely predictive. Over decades, reliability is most of what love looks like in practice.
What feels decisive but is not
Intensity. Covered at length elsewhere. Frequently a response to inconsistency.
Shared interests. Pleasant, nearly irrelevant. Hobbies change. How someone behaves when you are ill does not.
How much you have in common on paper. Two people can match on background, education, observance and geography and still want different lives.
Other people’s enthusiasm. Useful as information, not as a verdict. Your family can be delighted about someone who is wrong for you and uneasy about someone who is right.
Absence of doubt. Everyone has doubt. The question is what kind — see below.
Sorting the doubt
Two kinds, and they call for opposite responses.
Doubt about a specific thing. They do not want children on your timeline. They spend in a way that alarms you. Their family will always come first. This kind is information. It names itself, it stays the same over months, and it does not dissolve when you are feeling secure.
Free-floating doubt. A sense that something is missing, that there might be someone better, that you cannot picture it. This kind moves around, attaches to different things, is worse when you are tired, and usually has more to do with you than with them.
The first should be addressed directly. The second should be noticed and not obeyed — but also not suppressed, because if it never resolves over a long period it is telling you something, just not what it claims to be telling you.
The most useful test
Try to explain your reasons out loud, to someone who will push back.
People who are ready can do this. Not perfectly, but with specifics: because she tells me the truth, because I have seen how he was with his father last year, because we want the same house.
People who are not ready produce either a list of qualities that could describe anyone, or something that comes out as defence rather than description.
That test is more diagnostic than any amount of private deliberation, which is partly why talking this through with someone outside it helps — it is what Dating Clarity coaching is mostly for.
And then you decide
At some point the information stops accumulating and the thing left is a decision. Not a feeling that arrives, not a sign — a decision you make with what you have, knowing it is incomplete.
That is not a compromise on love. It is what choosing someone is.