If you are married to someone who has been an Irish citizen for at least 3 years, you may be eligible to apply for Irish citizenship by marriage. However, there is a residency requirement, meaning you must be able to prove you have resided in Ireland for 3 of the last 5 years prior to your application submission.
This is not an application for Irish citizenship by descent. Rather, it is an application for Irish naturalization, which is the same process that any foreign national would undergo after living in Ireland for a certain period of time. This process is also different from citizenship by descent in that several other factors are considered with an application, including purpose for residency in Ireland, citizenship of family members, and other ties to Irish citizens. The Minister will also consider an applicant's financial status and character.
Ireland's Minister of Foreign Affairs may, in his/her absolute discretion, waive the length of residency required based on a petition or letters of support, typically from folks in government or churches in Ireland. However, please note that we have not seen the residency requirement completely waived.
For more information, you can visit www.inis.gov.ie.