How can I accept my husband marrying another, knowing that the reason for not having children is due to me, and we have tried many times without success?

What helps in accepting life with a second wife:

1. Acceptance of Allah's legal ruling permitting polygyny, and submission to His decree. 2. Acceptance of Allah's universal decree, and certainty that what Allah has ordained is good, for "Wondrous is the affair of the believer, for there is good in every affair of his." 3. Whoever is content with what Allah has allotted him, Allah will be pleased with him and please him, for "Whoever is content, for him is contentment, and whoever is displeased, for him is displeasure." 4. Understanding the husband's need for a child and appreciating his patience in safeguarding the wife's feelings. 5. Seeking help from Allah and frequent remembrance of Him (dhikr) and prayer, for indeed, by the remembrance of Allah do hearts find tranquility.