Can you have a romantic relationship with the doggo or with Harold, or with any of the other male characters?, is it necessary to have the goo absortion kink on to have sex with Harold?
Do you mean a sex scene or do you mean dates? Yes for the former with both, no to the latter. At least not yet. The wiki has all the different events you can do with both of them.
And, generally, yes, you'll need to turn on the goo flag to do stuff with Harold.
