That can differ from person to person. To make a relationship work and last... You will need::: Good comuncatshinon*.. TRUST* And Honesty*.. And respect***. If any of these are missing then it wont last. Sometime its not working just means its not a good match and theirs a better match for you both;)
There's no average length for an intimate relationship. It depends on how you get along with the person. You can be in a relationship for the sake of being in one because of the things you are going through. Arguing is normal; it helps you know the other person better. Don't give up so early because of petty issues.
A relationship is just that. I don't know how old you are, but an intimate relationship can get complicated due to the range of emotions generated by either or both parties. To maintain a relationship you need one main ingredient, trust. If you both trust each other and want the best for each other you can cope with the day to day disagreements and remain as one.