I will write a bit on jealousy. Jealousy is very natural to earth animals. We are made to compete for the opportunity to spread our genes. I see much evidence that aliens also are in favor of spreading their genes. It is possible that human individuality makes jealousy possible. In a way, each human behaves as a separate alien race. Humans often compete for mating partners as do our animals. This stereotype of behavior is jealousy. It involves conscious and subconscious components. The subconscious component of jealousy is the emotion of jealousy.
It feels very much like hatred. The person protecting their mate becomes paranoid. They suspect other people to intend or unintentionally to be capable of taking away their mate and take preemptive actions to protect their mate and territory. This is very animal in humans. Our culture largely supports jealousy and the right of each human to protect their ownership of their mate. The idea of respecting the mate enough to let the mate to choose their path, is not very strong in human culture. I heard it first from Bashar, this was the time when it reached my consciousness. Now I see that the idea of respect to the choice of the mate has been around for hundreds of years, but it was foreign to me.
The idea of protecting the mate comes from the perception of lack and of being poor and unworthy. Few people who grew up loved and who feel abundant would find jealousy strange since they don't define their happiness by owning the mate. They may feel that they could be happy alone or they could find another mate. So jealousness is largely defined by culture of lack.
Jealous people feel righteous and can hurt or kill their rivals. I am pretty jealous by nature. I use my intellectual capacities by becoming paranoid and inventing who could be my rivals and how they can plot stealing my mate. This is my expression of care and love. I believe that I know what is better for my mate and that I would care about her better than anyone else. It may be self-delusional and often is. On other hand, we have plenty practical examples from our own life that not being paranoid and not protecting ownership of mates leads to losing them and ending up with no children and lonely. So it is not completely irrational. I am pretty sure that I won the competition for my mate playing by the rules and being reasonably protective and jealous. It is quite possible that I would have lost this competition if I have not played by the rules of it. So jealousy and competition for mates are not obsolete, many if not most humans still engage in this competition.
Not everyone engages in jealousy by nature. Sapolsky reviews several behavioral types. Some protect their ownership of mates and other types do not. Some are polygamic and some are not. There is variety. But most of the behaviors are optimized for improving the chances of an individual to combine their genes with best possible match, to spread their genes into best offspring and to give their offspring best start to ensure their future success in spreading individual's genes further.
The alternative to jealousy is trust, respect of choices of others and sharing. My outlook on jealousy and on the idea of spreading own genes changed much with my realization that the personality is not defined by genes, but instead is defined by the soul (and higher self). I figured out that genes are less important than souls and that we are much guided in our lives. So I don't have to compete and fight all the time, that I can be more successful by complying and cooperating with guidance. This is a radical change of attitude; many humans would have trouble understanding my choice. Religious people are familiar with this concept - to accept guidance by God. The New Age concept is to accept guidance by higher self, even though it is an alien and may be quite distant from Earth humans in physical appearance.
You may find it difficult to deal with humans who are still driven by ideas of competition for mates and jealousy. Realize that most humans don't understand the idea of spreading their genes. It is only geneticists who read Sapolsky understand that. Most humans are behaving the way they have been taught. If they were taught to share mates, they would share mates. If they were taught to respect the choice of the mate, they would do that. When hiring people for the work in the colony, take into account their need for sexual life and their upbringing to mate at any cost. For many people just being in the presence of opposite sex is enough. They could overcome their desire for physical contact. Take into account that if they are given an opportunity, and if there are aliens attractive by human standards, they would be very likely to have a crush on them or fall in love with them. People are flexible in their affections and would be able to fall in love even with aliens physiologically very distant, such as insects. Much of the love is happening on spiritual level and physiology may be disregarded. Take into account that human sexuality is strongly dependent on their self-perception, on their feeling popular, admired, approved, the status of their health, and many other factors. People are very dependent on approval of peers in their mating. I would predict that on colony, many people would feel much happier, much more admired, successful approved, healthier and their mating and flirting behaviors would likely be boosted. There are many ways to deal with that. Since you can read our minds pretty well, you should be capture the developments of sentiments very early. Adult people can often control their behavior and their mating instincts. You may give them instructions, explain expectations and describe ethics. I am sure you have certain rules and ethics for interspecies mating relationships and ethics in your world and you may want to educate humans on those rules and customs.
The need of humans for physical sexuality is substantial and solving it in the Colony would not be simple. Repressing the sexuality is possible, but this impairs health, energy flow and mental functions. I know the Greys in their hybridization program were abducting human girls to satisfy sexual appetites of their male hybrids. The male hybrids were also allowed to develop sexual relationships with human girls on the ground; these were called "special projects". The hybrids would be allowed to visit Earth and to have sex there. Abducting girls was completely immoral since they were violated against their will. For the colonists to be visiting Earth for having sex seems very far from your ideals as well.