Lol. I'm not gonna judge because I don't know Kuro at all, but if he is already married and is asking you to marry him (whether this is just for fun or not), it is still something to me. Unless you're okay with it. Then just get on with it and marry him! If it doesn't work out, drop him like it's hot. Online divorce has no consequence anyway, XD;
Even us members of the Girl Club are actually gentlemen. Gugu can still marry your avatar and personality though. This is, what we call in internet love, a leap of faith.