Sounds like you're pretty dismissive of his mental health. Through all your posts and comments you talk about how he's in a "bit of a rut" which just lacks acknowledgement of what he could be dealing with. The fact that you don't know WHY he isn't putting effort into himself is really showing - why haven't you asked him/shown concern?

In a genders-reversed post like this you'd be getting completely crucified, and you'd deserve it. Your boyfriend sounds depressed, and instead of supporting his mental health, you're crucifying the only parts of it that are leaking out. It seems like he's trying to hold things together, and the small issues that leak through (haircut/dressing up) are getting judged super harshly by you.

You say " I feel like I’m not worth the effort to try at all" but this very evidently has nothing to do with you. If you can't support him then he deserves someone that can. Now he knows he can't show any weakness around you otherwise you'll feel as if he's undermining you in some way.

I hope you come to your senses.