Kalista and Oathsworn

I have a quick question about Kalista being oathsworn to someone. Since there is a line that connects the both of you when you are within range, can the enemy team see that line? Because if they can, wouldn't that make it harder for surprise ganks with your support?

I've only played a solo custom on the PBE and I can't really tell from watching matches. I see them put wards in the bushes, but I just assume that's for possible in-lane jungle ganks.