At my wits end with my cat. Starting to resent him.

TL:DR – cat constantly cries, and absolutely NOTHING works. Starting to resent the cat and causing relationship issues. At a complete loss about options.

I’m at my complete wits end with my cat!!! He constantly cries. Non. Stop. We can’t take it anymore. He’s always cried a lot since he was a kitten, and he’s now 3 years old and nothing has changed. We have taken him to the vet multiple times and they can find nothing wrong with him. He’s an indoor only cat, and recently he started going outside to explore our apartment garden. He ended up running out the door one day, and since he didn’t stray far, we were giving him an hour outside each day to help burn off some energy. Now he wants to be outside constantly and will cry for literally hours when we bring him inside. He’s not one for cat toys, has never been interested in them. We have tried every single enriching activity and he does it once and never again. When we play with him (chasey or hide and seek) he’s bored after 5 mins. We tried Zylkene. We tried Feliway. Neither worked. We even trialled getting him a companion and that ended up terribly. We work from home 4 days a week and are around on the weekends. We are starting to resent him and it’s causing issues between me and my partner as we’re constantly stressed about him. We can’t give him up as pounds are full and he’ll be euthanised and none of our family members (with houses and yards) want to take him either as they don’t like him/hear horror stories from us. We’re just at a loss about our options. Videos attached is what he does all day