This really is a case of caught between a rock and a hard place. In your place, I'd opt to be with my partner, regardless of what she said. But that's just me. Going into treatment (chemo etc) is a very scary place mentally, especially if it's the first treatment. We all have preconceived ideas how awful chemo is, and the not knowing is the worst of the worst. After the first treatment, things settle down on the mental front.

If you decide to go, no one should judge you. That's a decision to be made between you and your partner. No one else. But yeah, regardless of what your partner is saying, he will be bricking it. Almost everyone does before their first chemo. Then there's also the slim chance he may take an adverse reaction to one of the drugs, which some people do. But this is something you won't know until after the first infusion. For my own peace of mind, I'd want to be there just in case, and could do without the scrambling to get back to her should something have happened.

i do not think it worth you going as you will not enjoy it x and deep down he more likely trying do right by you x just tell him truth it will not be enjoyable at this kind of time xxx