I've had an apartment I semi-shared with a female that my family knows nothing about...
In fairness, I have a "standoffish" relationship with my fam even though I love them and we stick together when necessary.....I never got the "motherly bond" so I don't feel obligated to tell anything to her just cuz she birthed me
My female friends know more about my sex life then my family
I told them to expect a baby within the next few years and we'll go from there...
So you asking strangers on the internet instead of just asking him directly? I could see why he's a private person towards ya'll. Type of family members to run and tell the internet and other people your kin folk business.
But honestly, he could just have social anxiety, high-functioning depression, introverted/ambivert, haven't met the right chick or could be focused on other things in life.
I know this is common though for brothas in the community who have it together and decide to stay single or keep their personal life private. So when people have nothing negative to say about you they get to making shyt up. I know Kevin Durant for example though he's famous get's called gay for being single or not dating.
When your cousin is home from winter break ask him to come to a bar with you and some of your friends or other family around the same age.
Try to get him to talk to a girl or invite girls to come if you know any. Don't invite him to a club or a lounge he probably wouldn't like those kind of settings. Do it in maybe a sports bar or a like dive bar when there's an event. You should be able to tell better in a social setting that's not around older family members.
It's not exactly anyone's business whether he wants to tell or not tell his people about his dating life.
The parents should wonder why their son does not have the type of relationship with them where he can confidently confide in them about anything. What was the guy's upbringing like?
23 is a young age and he's still got time. Maybe he wants to focus on education first and getting his money up before dating.
If he's gay or bi then it is what it is and people need to respect that.