Sun-Moon conjunctions, squares, and oppositions are some of the strongest indicators of traditional relationship, as indicated by the now-famous studies by Carl Jung. The Sun person usually takes the decider role, while the Moon person is usually in a supportive role. This dynamic is even stronger when it is reciprocal, that is Sun-Moon and Moon-Sun. When you have this, each of you sees the best in the other person.
Mars-Sun conjunctions, squares, and oppositions usually inspire a need to make the relationship physical and generate a sort of "buzz" of energy between the two people involved. Trines generate some physical attraction, but of a more pleasant kind.
Venus-Mars conjunctions and squares can inspire quite a bit of fuss and sexual interest, while Venus-Mars sextiles and trines offer a more pleasing, less in-your-face attraction.
Venus-Pluto conjunctions, squares, and oppositions are one of the most potent cross-aspects for sexual and emotional attraction. Although both people are generally attracted to each other, it is the Venus person who is the most enthralled and even obsessed with the relationship. Pluto-Venus is consumed with the attraction. Ultimately, it is the Pluto person who has the upper hand in terms of whether the relationship is going to endure.
Moon-Mars aspects can generate strong feelings that are often both physical and emotional at once, with the Mars person involved taking most of the initiative in the relationship, which can be very attractive to the Moon person (at least at the outset of the relationship). Later in the relationship, the Moon person may feel the Mars person to be crude or harsh.
Venus-Uranus conjunctions and squares can generate so much interest to the point of enthrallment, and often result in sexual activity between people before they know each other well. This can be a confusing and destabilizing contact in the long term, but these aspects generally inspire initial attraction. When these relationships last, the Uranus person is often seen as inconsistent by the Venus person and there can be many ups and downs.
Mars-Pluto conjunctions and squares are often powerful indicators of initial attraction and sexual intrigue. These trines don't necessarily draw people together, but once together, they are some of the most powerfully sexual aspects between two charts.
Ascendant-Ascendant conjunctions, sextiles, and trines, while not as strong as the indicators above, give a pleasing sense of physical harmony.
Saturn aspects are not fun, but add loyalty. This is frequently seen in long-term marriages and relationships where hardship is shared.