Here is my theory. (only refers to heterosexual but can probably apply across the board.
1) man = Adam; women = Eve
2) both looking for relationship/love cause they are fed up with either one-night stands, not getting any, single life, loneliness, friends all have partners, needing to be loved and cared for.
3) Adam and Eve meet up somewhere by chance or by arrangement: For example, dating site, party, nightclub, supermarket, friend set them up, work, mutual interest.
4) Adam and Eve are attracted to each other and arrange to go on a date in order to get to know each other.
5) Adam and Eve have some similar interests but also differences. If they are completely different then it may not work out. If they are too similar it may not work out. If they have differences and can accept them along with their bad habits then it may work out.
6) Adam and Eve continue to date/see each other and they start to form a bond. They care for each other, enjoy each others company, feel safe with each other, have arguments but can resolve them, go on holiday, go to the movies, start to develop similar interests, may start to dress the same, may even do that thing where couples are talking to other couples and they look at each other in order to get some kind of affirmation as in 'isn't that right Eve?', 'We had a great time didn't we'.
7) If things develop they may start to have plans for the future such as try for children, buy a house, move to the beach. This normally involves joining bank accounts and finances.
So I have kind of said obvious things and its a bit of a typology. The most likely is two people who are single and looking for a relationship, meet up and can see past the other person's faults and love them unconditionally.
