The Grand Trine makes him rather self-contained .. meaning he doesn’t need others to feel complete. Not saying he doesn’t want relationships .. just that they don’t matter quite as much as they might to someone else.
However, this Grand Trine involves Moon in logical, detached Aquarius, trine to Jupiter (cheerful and generally kind), and his Sun … his self-identity.
His Cancer Ascendant is not so important. Our Ascendant is the social mask we where in social situations when we are not yet at ease … as soon as we become at ease in that situation, we remove that mask and our real nature shows through. Cancer Rising tends to be very shy .. and the less comfortable they are in the social situation, the more shy they are.
Also, Moon conjunct Uranus makes him emotionSunally changeable – perhaps even unstable. And that is hard on a relationship.
As well, what he needs out of a relationships (Venus) internally conflicts what how he is emotionally, so he finds it difficult to be satisfied in relationships. At least, until he resolves this inner conflict.
Venus is with Mercury and together they are in a square aspect with Uranus .. he doesn’t like to compromise and doesn’t like to commit either. Also Mercury square Uranus is usually someone who thinks they are always right .. may even be arrogant about it.
He also has a t-square of Jupiter opposite Pluto, both squared by Mars. This makes Mars THE strongest factor in his birthchart. And Mars is the planet of both how we take action (going after whatever we want) and how aggressive we get if we are blocked from getting what we want. Mars is in Virgo, which is not a very aggressive sign, so he’s not likely to be out-and-out aggressive. But he gets irritable. The square to Jupiter means he takes unwise risks, and to Pluto .. well okay, that just puts it out the window … when he gets mad .. he gets MAD. Perhaps even physically violent.
Some of my best friends have Moon in early Aquarius. That is because my Jupiter is conjunct their Moon, so I look kindly on them and forgive them anything. I like their logical way of dealing with life, and as a friend I am comfortable with how emotionally detached they are. But I have seen them blow ... because they try to be logical, when their emotions DO overwhelm them, they react very strongly. And in the case of this guy, with Mars being the focal planet of his T-square .. even more so.
YET, astrology is only an influence, and all it indicates is how we will be IF we look inward to change and grow. No one is "doomed" to be pushed around by their natal chart influences. But it is up to YOU to get to know him and see where he stands on this .. how much he is influenced by it, and how much he has taken charge of who and how he is (especially his emotions).