*Companionship : she had a dog for that.
Love : gets that from her kids
Fun: gets that from her friends
sex; I do have a Penis, (but I understand replacements are available)*
I didn't have a dog, or cat, or kids. Friends yes, but I've never been someone with a bunch of giriy friends I do stuff with every weekend. Also, as friends all had kids seeing them meant going to the fucking zoo, so .........
Everyone has explained the sex part.
It's companionship, knowing someone has your back, feeling that if you're sad you can just call that person (there is no person in my life I could call just because I was sad, even if I was very sad I can't think of anyone).
Also to help with decisions (I'm trying to plan a new bathroom, it's tedious, I hate it, I have no-one to bounce ideas off), to treat you now and then, bring tea in bed, sympathise if you're ill, drive you home if you want a drink, go on holiday with, support you through a bereavement, visit your aging parent with you and therefore prevent her harsh comments on how fat you are because even she draws the line at being cruel in front of other people........
And do all that for them too because caring about other people is also fulfilling.