- I agree a full/half/no strength sexuality scale for the two genders would make sense (or, since there are two bits available, make it strength 0-3).
- It would make sense of personality affected the rate at which they progressed to friendship; "only forms tenuous relationships" would be slow, and possibly decay fast. Similarly, some dorfs ought to quickly form a lot of shallow relations that were maintained easily.
- Other personality traits (possibly in conjunction with the set of the previous level) would affect the progression to the lover state ("constantly ablaze with lust" would probably make this fast").
- A third set of personality traits (again in conjunction with the first level, but probably not the second) would affect the progression to the married state.
- I'd argue the higher levels ought to affect the lower as well if positive: a lustful dorf ought to speed up the friendship gaining in order to reach the lover state (and the same logic for family formers). If possible, this should be selective so the speed gain would be applied only to eligible target (correct gender, age difference, race [I think that's currently mandatory, even though Cado seemed to be human and he hooked up with a dwarf {who probably was centuries older than he was}], and lover/maritial status).
Obviously, the above is seen from the perspective of one party. Currently relations can be asymmetric (one being friends with another who has no relation at all back to the first one), which probably is a bug. Lover/marriage are always been symmetric, to my knowledge and should be reached only when both parties have reached that point. It does make some real world sense to have asymmetric relation though: there are some people who consider themselves to be friends with most people they meet, while the other party can consider these people to be someone they vaguely know who they are.
Some human behaviors do not apply to dorfs, however. No sex outside of lover/wedlock relations (and reproduction only within wedlock), a strict single marriage total, etc.