Whatever their tribe or their history, elves are all of one race. Only the Wolfriders have a claim to being a different race, and that rests solely on their wolf blood.
Elves are aliens. Their perceptions, understandings, and morality is not the same as it is with humans. Do not make it so.
Time
All elves, even Wolfriders, are effectively immortal. Yes, Wolfriders may die of old age, but that has seldom been tested. They usually die at their own will, or due to accident. With so much time before them, seldom does an elf have any sense of urgency. Life threatening situations - starvation, drowning, being gored by a bristleboar - may be urgent, but most issues that arise are well-considered. Time means little to elves, even Wolfriders.
Sexuality
Elves are not constrained by human perceptions of sexuality. Sex, to them, is all about sharing pleasure and they do not define themselves as heterosexual, bisexual, or homosexual. Two men or two women sharing pleasure with each other is just as natural and acceptable as a man and a woman. Groupings of more than two are equally accepted. Sex, the sharing of pleasure, is life-affirming and a celebration of the senses. Monogamy is not an expectation or the norm. Lifemates may share a joining with others and feel no guilt, and their partners no jealousy or resentment.
Familial Relationships
The elvish numbers have always been low, and for this reason familial relationships - while loving and close - haven't precluded lovemating or lifemating relationships. Timmorn bred with the full elves, but also to some of his offspring. Inbreeding is not a concern since Recognition and the magic of the elves themselves will keep their race viable by correcting any harmful mutations that inbreeding may otherwise cause.
Incest is a social concept formulated by humans, and it is only within our society that is considered 'bad.' Even in our ancient past it was not anathema. Today, we think nothing of breeding animals to their siblings or parents to strengthen the offspring.
While now it is extremely unlikely that father would lay with daughter, or mother with son, because of the parental relationship formed between the parents and the offspring and the available number of other lovemates and lifemates, the potential for mature, sexual relationships with aunts, uncles, close cousins, and the life is possible. After an elf reaches physical maturity by the age of 20, they have an unimaginably long life stretching before them.
Expressions of Affection
Elves send, and in the sending all layers of emotions are shared. For this reason, they do not have to verbalize what they feel. They do not say, "I love you," because they already know, more truly than words can say. They may call each other 'Beloved,' but that is a pet name, like sugar, honey, babe, or sweetheart.
Nor do elves 'kiss.' Giving a word to a natural physical expression is unnecessary. While they may do something that is kissing in all but name, they don't give the action a separate identity that makes it more, or less, than it is. Elves are very physical and take great comfort in touching each other.
Children
Children are rare and precious to all elf tribes. While there is genetically one mother and father, the entire tribe participates in the teaching and raising of all cubs.
Information partially pulled from ElfQuest: the Roleplaying Game (2nd Edition) and otherwise adapted as needed by the Holt managers.