Noble Marriages

The marriage traditions followed by most of Flautarion's nobility were perfected over the centuries as a way to foster alliances between kingdoms and produce the next generation of princes and princesses while preserving the right to love and have relationships to whoever one's heart desires. The couples are paired up based on whether they can have children together, and they are expected to do so eventually, but they are also free to have as many lovers of however many genders and body configurations as they want on the side, and those lovers are also considered part of the family.
Noble families will send marriage proposals to other nobles as soon as a child is born. In the case of royal families in particular, negotiations might begin during pregnancy. Once a deal is agreed, the families involved will make an effort to have the new couple spend time together from early on and foster friendship. It is in everyone's best interest that the couple gets on well, as a happy marriage is a prosperous one. The children involved in the marriage agreement are allowed to call it off when they turn 16 if they think the partner chosen for them is not someone they can trust or consider a friend.
If the couple decides to go ahead with the marriage, the ceremony usually happens when the youngest one is at least 16 years old. In the case of a marriage of two royals, the festivities last for a week, taking place in the kingdom where the couple will spend most of their time (this would have been negotiated as part of the initial agreement at the children's birth). The day of the ceremony itself varies from kingdom to kingdom. Most tend to have the ceremony in the 4th day of festivities, or as its closing event. Neponia is the only kingdom that starts festivities with the ceremony (and the running joke is that Queen Morgana does it this way so that she can kill her new husband during the festivities and have the funeral as the closing event).
The couple is expected to not be "intimate" until the ceremony. They are encouraged to spend as much time together until then, but are always accompanied by a chaperone. The couple is also expected to not have any lovers prior to the marriage (though this rule is sometimes overlooked when the two lovers cannot have children together). The more traditionalists also expect no lovers until the first child is born, so that their parentage is clear.
All children born of nobles receive noble titles, even those born from lovers who are not of noble blood (such relationships are allowed, though not always encouraged). In the case of royal families, the children of lovers will also be considered princes and princesses, but will not inherit the throne. Lovers (noble or otherwise) are considered fully part of the family, and thus are expected to be as involved in a child's upbringing as the birth parents.