Which gloryhole? Caleb's or in Farmstead?
With Caleb it's easy, just keep increasing his likeness (Bring him beer and flirt with him), and make sure to talk with Bernard if anything new pops up in both their dialogue options, and one day the gloryhole will appear in the Barn. There's a bonus if you have an Encouraged Logan.
With Farmstead, (This is assuming you're finished with Country Road event) just wait until night time and go check on the fence at Farmstead. The gloryhole should be there and just keep peeking though the hole until an event happens. If you still don't have the gloryhole option for Farmstead, make sure that Logan has visited Ste (whether it's Encouraged or Discouraged) then the option to check the fence will appear after. With the Discouraged Logan though, you'll have to make the gloryhole yourself for 14 days before any events could happen at the fence.
Hope this helps.