Marriage, or its equivalents, vary from species to species.
Anyeli
Marriage for the Anyeli, more often than not, is more about repopulating the ranks than for pure love. Couples are officially expected to produce at least one child, and the marriage contract they sign reflects this (essentially forcing them to stay together, often on pain of a court martial, especially for those still in active military service) until a child is produced).
Love is still a big part of the equation, of course. Anyeli are not forced to marry, only refused the right to divorce until there are off-spring.
Once a child is in the works, the marriage is theirs to do with as they will. They can petition their superiors for a divorce (which can be refused during times of war when their faction leader might wish for greater numbers); they can stay together; or, as happens frequently, they can live separately for intermittent periods, either by choice or assignment. (It is actually quite common for married couples to not see each for years or decades but still consider themselves monogamous.)
Dracovari
Dracovarian marriage is a formal, legal contract between two people who wish to spend their lives together as a family unit, with or without love. The contract has a clause which voids the relationship if one or the other should find their lifemate.
The adult lifespan of a 'Varian is such that the marriage contract does not include the word "forever", yet many couples remain committed for the duration.
Nymphs
The Nymphs call it "hand-fasting" because a Sylph literally ties their hands together as a symbol of the promise they make to each other.
Nymphs can hand-fast with either gender, but it's not just a marriage ceremony. Hand-fasting can be a ceremony for love vows, which can differ from couple to couple (with some being more committed to monogamy than others), but it can also be a formal promise between Nymphs who wish to bond with the same demesne.
Therians
Therians don't technically get married at all, not by any legally binding document; their marriage is more of a social union that varies between clans. Some choose a "mate" and swear before their clan leader to stay together for life, while others are allowed to mate at will with no interference or supervision.
Zanaryans
For Zanaryans, marriage is distinctly political and usually arranged by the patriarch (though the wives actually do most of the match-making). Both females and males are raised to follow the patriarch's decree, knowing that such a marriage is the very best political arrangement available to them.
As a result, Zanaryan weddings are really for introducing the newly-weds as well as making the contract legal, so they are long and drawn-out affairs. (Some of the wealthier and more influential Houses have weddings that last a full week!)
No expense is spared for fear of appearing poor or "common".