being a male, I would only use xoxoxo with people who I would actually hug and kiss, so not just friends, so maybe girlfriend/wife/mother. xoxoxo is probably used a lot more by women than men. girls use it a lot more frequently though. xoxoxo is definitely a "cute" thing, and the hugs and kisses are not especially sexual.
I would be careful with its use. While I think some teenage girls might use it more promiscuously, adults would only use it when they would actually give someone a kiss in person. If you would shake their hand upon meeting them, you shouldn't use this in writing.