[bgill]

Not merging. Just a one night stand.

[al baby]

But is it consensual ?

[JustaTech]

Galaxies are made of almost entirely nothing, compared to the vast volume they occupy. A galaxy "collision" is like nothing running into nothing. Galaxy mergers occur over many millions of years and don't create many stellar collisions if any at all.

Civilizations could form and advance to the same stage we are now, before they'd even have a clue that they're in the midst of a galactic merger. It just wouldn't make any difference, even over a span of generations.