"Whatever the case, after the divorce of Ptolemy, Arsinoe II then married her younger brother. As a result, both were given the epithet "Philadelphoi" (Koinē Greek: Φιλάδελφοι "Sibling-lovers")."
(1) She is married to Lysimachus.
They got married about 301 BC.Source 3
"At about age 15, Arsinoë married King Lysimachus"
(2) She is married to Ptolemaeus Keraunos.
They got married about 282 BC.Source 2
"In 281 BC, Lysimachus died in battle and Arsinoë fled to Cassandreia (Κασσάνδρεια). There, she married her paternal half-brother Ptolemy Keraunos"
"As Ptolemy Keraunos was becoming more powerful, Arsinoë decided it was time to stop him and conspired against him with her sons. This action caused Ptolemy Keraunus to kill two of her sons, Lysimachus and Philip, while the eldest, Ptolemy, was able to escape and to flee north, to the kingdom of the Dardanians.
A gold coin shows paired, profiled busts of a plump man and woman. The man is in front and wears a diadem and drapery. It is inscribed "ΑΔΕΛΦΩΝ".
Head of Ptolemy II Philadelphus with Arsinoe II behind. The Greek inscription ΑΔΕΛΦΩΝ means "[coin] of the siblings".
Arsinoë sought refuge in the Samothrace temple complex, which she had benefited during her tenure as queen.[11] She eventually left from Samothrace for Alexandria, Egypt, to seek protection from her brother, Ptolemy II Philadelphus.[12]
It is not known which year she left for Egypt. She may have left so early as 280, directly after the murder of the younger sons, or as late as 276, when the claim of her eldest son to the Macedonian throne had clearly failed after the succession of Antigonus II Gonatas.[6] "
The couple were divorced in 278.
(3) She is married to Ptolemaeus II Philadelphus.
They got married about 273 BC.Source 4
https://nl.wikipedia.org/wiki/Arsino%C3%AB_III
https://en.wikipedia.org/wiki/Arsinoe_II#Queen_of_Ptolemy_Keraunos
https://en.wikipedia.org/wiki/Arsinoe_II#Queen_of_Lysimachus
https://en.wikipedia.org/wiki/Ptolemy_II_Philadelphus#Marriages_and_issue