Many people wrote to the Rebbe unsure whether to go ahead with a shidduch. His guidance:
Doubts are normal; approach them calmly. Anxiety before marriage is common and often comes from the seriousness of the step itself. Talking it over with friends who married recently can bring reassurance (IK 5085, 8261).
Both mind and heart matter. If the logic says yes but the heart doesn't agree, that feeling should not be ignored (IK 6083). If there is no feeling after several meetings, wait for clarity: sometimes more meetings help, sometimes a break (IK 2535, 10498).
A break can bring clarity. Pausing contact for several weeks and then reassessing with a fresh perspective often shows one's true feelings (IK 3941, 8738, 10936).
Don't rush, and don't hesitate endlessly. Consider carefully, act naturally, and rely on Hashem's guidance. Avoid distractions and perfectionism, and focus on the essentials (IK 1467, 5413).
Seek advice from people you trust. The decision belongs to the individual, together with parents' input and trusted friends who know the situation. Refrain from negative statements about a suggestion (IK 2418, 6231, 8774, 10364, 10497).
Trust in Hashem's providence, even when the outcome differs from one's hopes (IK 9582, 10790).