Nadi dosha is definitely not good, it can ruin marital life. The importance of Nadi dosha can be seen from the fact that Nadi dosha has Maximum points in Ashtkoot Guna Milan.
You should check if Nadi dosha is complete or not by checking Paad Vedha. If there is no Paad Vedha, then marriage can be done, there will be no problems.
You can check if Nadi Dosha is present in the link below.
Horoscope Matching | free kundali matching for marriage
Blessings,
Navneet Khanna
Astrologer