I believe in sincere and not strong relation. As long as the relation continues, this should be sincere. There should be no abrupt breaking even though these may fade. Also if you are in a job entailing frequent transfer, your relations will continue only till you are at the station. These end at Railway station. The most important thing is that even temporary relations should be sincere.
It takes time for any relation to develop and flourish. Things like communicating daily, showing affection and understanding plays an important role for your relationship to be bound stronger and tighter....
I do my best and all that is proper and fair and also polite. This is how you maintain relations. In spite of good behavior, relations may be damaged. This depends on all parties concerned and not on a particular person.
I thing trust is the base of any relation.Your relation can only continue if you trust your partner.Stronger is the trust, more rock solid will be the building of the relationship.