The basic nature of the planets that get involved in a combination for affairs decide what type of partner a person has. Now as we know in most cases just one planet does not define an affair so depending on the planets involved in the dasha at the time of the affair the qualities of the partner can be judged as follows:
The native will have an affair with someone who will be in a higher position. Possibly in a government job or superior position like a boss or manager. Most probably a higher position than the native himself.
Moon will ensure that the partner involved will have the same position as defined in Sun but that the person will be classically beautiful and might be older that the native.
Mars will ensure that the partner involved is in a position of authority like a policeman, judge, security etc. They will have a uniform requirement for their work or for the industry they are involved in.
Jupiter will ensure that partner in the relationship will be in a position of mentoring like a trainer, teacher etc.
The partner will be from a different work culture and would be a service based person. Depending on the placement of Saturn 7th Lord and 7th house the person could be older than native.
The partner will be much younger than the native and will be have had multiple affairs before joining up with the native.
The person will be well educated from a good family background and will be classically beautiful and soft spoken.
Rahu and Ketu
The presence of either of these two would be make the relationship unconventional like being from a different religion, one of the 2 parties being diseased, etc.