There's nothing saying that you won't get married while still in uni :p
Like one of my pdhpe teachers in yr 9, he got married last yr of uni, was only 22
Planned on getting married at 21 but he found 'the one'
He doesn't have to 'like' you, he could just be staring because he was attracted to something about you on the night, maybe when he sees you next he won't find that 'thing' in you anymore and wont look at you again.
Most likely he found you attractive and was staring at whatever he liked about you the whole time.
The awkward moment when someone's staring and you look at them and then look away and look again then look away again etc...