Does remarrying after a separation agreement affect an ex-spouse's ability to claim support from the estate?

Not automatically, but it can be relevant. A separation agreement that validly released estate claims generally continues to apply on its own terms even after either party remarries — remarriage on its own doesn't revive or extinguish a properly negotiated release. What actually happens depends heavily on the agreement itself: whether it addressed future changes like remarriage, whether the release was clear and comprehensive, and whether it still holds up on the general grounds courts examine, such as fairness, disclosure, and legal advice at signing.

Remarriage can matter indirectly, though — it changes who else might qualify as a dependant of the deceased, such as a new spouse, which affects how a limited estate gets divided among competing claims even where the ex-spouse's own claim is weak or released. An ex-spouse considering a support claim after a former partner remarried, or a new spouse concerned about an old separation agreement, should get legal advice about how the specific agreement's wording and the estate's full set of dependants interact, since this isn't a one-size-fits-all answer.