Why is Ixion(biome 2 boss) way difficult in multiplayer

I find almost all the bosses are easier while playing with a friend except Ixion all the other bosses we were able to easily finish off after a couple of tries but Ixion was just hell bent difficult I got frustrated and finished off in my game in solo mode and he felt dead easy compared to multiplayer and then me and my friend picked it up as a challenge and tried to defeat him in multiplayer only and it literally took countless tries and 3 weeks to finally beat him is this normal and why specifically he is difficult in multiplayer