I would go to the GP as PPs have suggested.
Therapy is very good with helping to rationalise emotions and something that sounds like it may help, is looking at ‘self’ and ‘other.’
So instead of self: he doesn’t love me, doesn’t care about me, if he did he’d do this, this and this.
Think of the other: he is looking after his health, he doesn’t want to be ill. No one would intentionally make them self ill - who would want to intentionally and knowingly risk not having a good weekend?
Feeling like poop, all groggy with a banging headache, sore throat and blocked nose. Does he have plans that would fall through if he was ill? Perhaps he doesn’t do very well with being poorly - some people are troopers and carry on, others would be laid up all weekend feeling terrible. Would he pass this onto other family members who are perhaps more vulnerable?
This example is a tad easier to work through the ‘other’ than most, as he’s already given an answer, in black and white terms, as to why he’s not seeing you as much at the moment. So in a way, you already have the ‘other’ available to you. Much harder in other situations when the ‘other’ isn’t specified as explicitly. Still can be done though, and this practise really helps me.
Journalling, therapy, getting outdoors, having interests/hobbies, exercise and meditation all help too. Best of luck.