I may be crucified cos of my views on this issue,but from my small research,I've seen that inter-tribal relationships are the best.This is because when you find love in someone who has a different cultural mentality other than yours,its something worth it.Personally,I come from the south-south (calabar - to be precise),but all the girls I've gone out with (they are not many oohhhh) have either been yoruba girls,or from the middle belt.Permit me to say this,yoruba girls are really good when it comes to issues of relationships

Inter-tribal relationships isn't the best as you said because most patents won't allow their children marry outside their tribe.

Take an example: an Igbo girl getting married to a housa boy do you think both parents would support that wedding?
They may be in love but the parents are not willing to lift a finger to support their relationship which makes such relationsip nothing but pain in the end.