First time I cruised was with colleagues. We had a wonderful time, no doubt. But then six months later, I went by myself. And I had the time of my life. You get the best cruise experience, by yourself imho. You're more rawn to other people. If you're travellin gtogether with others, you're very likely to stick within your own group and are more hessitant meeting up with others.
I won't share my cabin with anybody else. Or maybe one day, my girlfriend. But only if she ask real nice, though