What effect did the marriage have on their lives?

The marriage binds Romeo and Juliet more tightly together. Had they just met and spoken of love but not married, Juliet might have had a different reaction about Romeo killing Tybalt. When the Nurse challenges Juliet to condemn Romeo, Juliet counters with "Shall I speak ill of him that is my husband?" Had he not been her husband, would she have turned against him? Perhaps not, but the marriage seems to solidify her loyalty.
The marriage also increases the secrecy. Not only have they met and kissed, but they married in secret! This secret compounds the horror Juliet feels at her father promising her to Paris; she is already married.
The wedding also implicates Friar Laurence and the Nurse for the later tragedies. These two adults know about the wedding and, in fact, facilitate the secret wedding of two young people. Admittedly, the relationships between the parents and their children already seem strained, but this huge secret adds to that gulf in understanding. That distance could be why neither Romeo nor Juliet turns to a parent for guidance.