Im an international student. what this mean..?

Question

It's not easy liking someone who is really on the fence about you.

Answer 1

Being "on the fence" means you are neither in or out, you are straddling the issue. Not on one side or the other, undecided.

Answer 2

It means that it isn't easy to like someone that may or may not like you.

If you don't know if someone likes you - and you think they may even dislike you - it's hard to like them.

Good for you for studying out of your home country. Hope you're enjoying it!