Because that's how gravity works.
Galactic Civilizations happened in 2003.
Galactic Crusader happened in 1990.
Galactic Trader happened in 1987.
Galactic Warriors happened in 1985.
Galactic Pinball happened in 1995.
Avengers in Galactic Storm happened in 1995.
Body Blows Galactic happened in 1993.
Galactic Empire - Brøderbund video game - happened in 1980.
Yes, galaxies can orbit each other in space. This phenomenon is known as galactic interaction or galactic cannibalism, where the gravitational forces between two or more galaxies cause them to orbit around a common center of mass.
No more than usual, at least in the US.
It's called an Intergalactic collision or Interacting Galaxy. Where a galaxy is consumed, or more correctly "merges" is called galactic cannibalism.
you would die. Huh - more like that would be cannibalism...