Short answer. Yes. Family Code Article 81 voids stipulations made in consideration of a future marriage if the marriage does not take place, but it expressly carves out an exception: stipulations that do not depend upon the celebration of the marriage remain valid even after the wedding is called off.
What the law says
stipulations that do not depend upon the celebration of the marriages shall be valid
Family Code, Article 81 — Effect of the Marriage Not Taking Place on Settlements. Read the full provision →
The general rule: no wedding, no effect
Article 81 sets a default consequence for a marriage settlement when the wedding never happens. Everything stipulated in the settlements or contracts referred to in the preceding articles in consideration of a future marriage, including donations between the prospective spouses made therein, shall be rendered void if the marriage does not take place. The logic is straightforward: a stipulation made specifically because the marriage was going to happen loses its reason for existing once that marriage does not occur, so the law treats it as void rather than leaving it in force.
The exception for stipulations not tied to the wedding
The article then draws the line you are asking about directly: however, stipulations that do not depend upon the celebration of the marriages shall be valid. Not every clause in a marriage settlement is written in consideration of the marriage happening. A provision that would apply whether or not the wedding takes place, one whose purpose or effect does not hinge on the marriage being celebrated, falls outside the void rule and keeps its legal force.
What actually decides which category a clause falls into
Whether a specific stipulation counts as dependent on the marriage or independent of it comes down to what that clause was actually meant to accomplish, not simply where it sits in the document. A donation conditioned explicitly on the wedding taking place is squarely within the void rule. A separate arrangement, such as one settling something between the parties regardless of whether they marry, is the kind of provision the exception is meant to protect. Reading your settlement's specific wording is what determines which side of that line each clause falls on.
Why donations get called out specifically
The article singles out donations between prospective spouses because those are the clearest example of a stipulation made purely in consideration of the marriage happening, and therefore the clearest example of something the void rule is meant to catch. That specific mention does not shrink the exception; it simply flags the kind of stipulation most obviously tied to the wedding taking place. Clauses that serve some other, independent purpose remain governed by the general exception for stipulations that do not depend on the marriage being celebrated, regardless of whether they happen to appear in the same settlement document as a conditional donation.