He seemed to resist becoming involved at first, so why did He change His mind?
John 2:1 - 11
YLT - 1 And the third day a marriage happened in Cana of Galilee, and the mother of Jesus was there. 2 And also Jesus was called, and his disciples, to the marriage.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
The answer is not given in scripture as to why Jesus became involved and human conjecture is meaningless. However, it is important to point out that this portion of scripture is the first (1st) attestation (witness) that Jesus Christ is divine (God in Flesh).