Not all unmet needs are worth considering. It depends not only how realistically easy to fulfil they are, but also if the dwarf in question is
stress resistant or not, and if that need is
important to him or not. Ultimately also if the dwarf is important to YOU.
Regarding
stress resistance, if you use Dwarf Therapist, you can check
Depression Propensity. Low value most probably means the dwarf will be perpetually happy, high value means he will be perpetually unhappy, even if most needs are fulfilled. You don't need to check these values in DT, if they are way below/above average, Dwarf Fortress on its own will give info in their description (In Overview and in Personality/Traits). For example one with high Depression Propensity will have "Depression-prone" in Overview and something like "She is frequently depressed after experiencing trauma" in Personality/Traits. There are also similar traits,
Stress Vulnerability (Easily stressed) and
Anger Propensity (Anger-prone). High values are bad, and you may need to manage the dwarf (or goblin) more.
Whether the
need is important you can see in Thoughts/Recent Thoughts (thinks like "dejected" or "self-pity"). You can check how important the emotion is here:
https://dwarffortresswiki.org/index.php/Emotion, if it's closer to 1 (or -1 for positive emotions) it's more important than when it's closer to 8 (or -8). So the lack of family member or lover may be not that pressing as it seems.
Now, if you have an important dwarf, who is prone to depression, and don't wont to ignore it, you need to manage the dwarf. I have such a dwarf in Military Commander, who unfortunately has Depression Propensity at 98 (had lower before some bloody event increased it). Apart from general things (like good bedrooms with items made from liked materials, good food and drinks available, clothes, tavern etc.) I micro-manage only two things: workshops for dwarves who want to be creative, and temples.
I make individual workshops for certain dwarves (they need to be "master" and only the master can work in such workshop), and order to make item or a few per month in these workshops.
Temples are more involved, but apart from general temple, I make temples for popular gods, as well for popular religions (which can be dedicated to these same gods, but require a different temple). In temples I make displays, where I put stuff like menacing steel spikes to increase value if necessary, but this only if the worshippers want such big temple.
Now, I noticed that most dwarves who are unhappy in a generally very happy fortress are military dwarves, like my commander. The reason is often that they don't fulfil they need when off duty, because they train instead. These needs are like meeting with family, friends, socialising or praying (quite religious dwarves are notorious for that). The way to make them fulfil they need is to move them, temporarily at least, to a squad which doesn't have barrack assigned. When the dwarves are off duty, they will try to fulfil the need.