Why are marriages not encouraged during the Days of Awe between Rosh Hashana and Yom Kippur?
While there is no prohibition against marrying between Rosh Hashana and Yom Kippur, it is customary to refrain from doing so. Because these are days of judgment, we want to direct our primary energies towards repentance: Reflecting on our performance during the past year, and taking steps to improve.
Once, before Yom Kippur, the famed Rabbi Yitzchak Blazer saw one of his students buying an etrog, one of the four species needed for the Succot festival occurring shortly after Yom Kippur.
"Repentance you have achieved already?"
Rabbi Blazer asked him. His point was that, unless you have attained perfection of character, you should direct your primary focus towards repentance during these days, and leave other matters for after Yom Kippur.