not eating well

I'm kind of having some food issues with my 1 year old lab. When he was a young puppy he would eat all his food in seconds, like a vacuum and never gave me a problem, however the last 4-5 months he's not eating well at all. There has been alot of stress in our lives in the last 6 months, don't know if that has anything to do with it. My boyfriend and I separated so Taylor doesn't see his dad at all and I know that really has affected him. Other than that, I've tried putting beef broth on his food, he seems to like wet food but it tends to give him the runs. I've tried some different types of food and gone back to the original and he still won't eat it. He doesn't get many treats so he's not spoiled by human food or anything. He's getting kind of skinny so if there are any suggestions it would be appreciated.

I'd take him to the vet to be thoroughly checked out, in order to rule out a physiological cause.

I agree w/ queen vee. If that turns out ok the vet may have some suggestions for you too.
Persoanlly I would feed him a high quality food so he gets as much nutrients as possible & the better foods ussually taste better too which may help him eat more. I would not spoil him w/ extras added to it as then he may get too used to it that way, it is healthier for him to eat just dry food.
Also try leaving out food 24/7 if you do not do so already, then he can eat whenever he wants.
Also by spending a little extra time w/ him everyday to help him feel better, possibly do some really vigourous excersize to try to increase his appetite. If his dad did special things w/ him maybe you can do the same activities with him too.
It is hard on animals too during a seperation so just try to act like evrything is normal & give him an extra walk everyday to help comfort him. He should be his normal self soon if it is not medical.
If there is other stress going on that may be part of the problem too, which may require doifferent techniques