I have been studying this relationship system for several months now ([url]http://www.the16types.info/vbulletin/content.php[/url]) and would like to recommend it. It has helped me gain a lot of insight into people's interactions which previously I was clueless about: it explained why some people experience a lot of misunderstandings, how to identify and attract the types of people that are good for me, why some relationships are asymmetrical i.e. one partner loves another more than the other way around, why some people are draining to spend time with while others are energizing.
How it works: First you type yourself using one of 16 personality types using profiles. Names for the types consist of 4-letter designations, such as ESFj or ISTp. Then you type your friends, lovers, family members, co-workers, etc. Each personality type has a specific theme of relations to another type that you can read about here: [url=http://www.the16types.info/vbulletin/list.php/category/28-Intertype-Relations]Intertype Relations[/url]
If you have any questions please ask, I'd be happy to answer. This system is absolutely free too (they don't ask for any money, it just takes several months to get good practice in typing people).