When I first met DP he wore scruffy, oversized clothes that just looked awful. He had a job interview once and was going to go dressed in ancient scruffy, 3 sizes too big, jeans with a horrible old grey t-shirt with dragons on the front 
I got him kitted out properly and he got the job. Since then he started making more of an effort, chucked out his old big clothes and bought nice, modern stuff that fit him properly. I never wanted him to dress like a superstar, just to dress DECENT.
Anyway he seems to be going back to the way he used to be. A number of times now he's come to pick me up in jeans with a hole in the knee and now he's got this obsession with buying old jumpers off ebay or from car boot sales for £1 which are blatantly years old, ill fitting and scruffy. At first he said these jumpers were just for the in the house but he's wearing them constantly. We went out for coffee a few days ago and he wore this old jumper that was bitty to hell, right up his back from where it had obviously gone out of shape years ago and just looked silly.
I'm embarrassed to go out with him like this. Do I tell him or just reconsider the relationship entirely rather than trying to change someone who obviously doesn't want to change?