..could many reasons.. but I don't see why they have to admit their relationship, it's their personal life na :-)
..many reasons ranging from shyness, genuine dislike to announce their private life to the world, keeping private things private... and relationships are never simple -
- courting stages are long,
- beat around the bush for long time before committing,
- take long time before engaging,
- even long time for marrying,
- and the confusing relationship dynamics where guy and girl keep each other confused as to ---
a) whether they are friends,
b) if they have a 'chance',
c) FWB situation where one of them is in continuous denial and hopeful,
d) some have a roller-coaster ride with on-again-off-again dating,
and so on...
..with the aforementioned complexities, it is natural... plus, basically, they don't have to say what they're doing in their private life..