Why not find a "hobby" which involves the day ..... obedience classes, dog agility, or think about doing the Good Citizen course, or even joining the Pets as Therapy scheme ................ then you might not feel so back when you leave him sometimes ................... and better training with regard to the weeing will help - but agree that much more than 5 hours is too long. Plenty of dog sitters/walkers out there. Do you not have a responsible teenage relative nearby who would be glad of a couple of pounds to walk him or check on him if you're having a big night out - or have a big night in occasionally, where everyone comes ot you and you cook or order takeaway ...... and if you do this at another friends house, can pooch not join you??
Failing this - find him a home where he can have more human interaction ..... I don't agree with some posts you have received which are negative towards you ........... I believe you care about your dog and feel bad about leaving him etc etc ....... so unless you can change the way you social etc, he needs to go somewhere else - animal charities will help fin new home - but try and hold on to him until he goes to his new home, it would be such a shame if he had to go into rehoming kennels, as although they are well looked after, they are very stressful places.