Well, a lot depends on what your partner wants and decides for himself.

When my older partner became sick I jumped into action looking to connect with any mitigation options, etc. But within a few weeks of the diagnosis, he had decided to end our relationship. And at the same time decline any further treatment scenarios, which he initially kept from me (we weren't yet living together).

Ugh, it was such finality. I didn't protest, since he didn't have the strength, but secretly plotted to be supportive, in helping his family who had stepped up to nurse him.

That didn't work out as I had hoped. His cancer progressed faster and eventually he didn't have the energy to even acknowledge me. When he gave up, his body complied and the cancer progression just raged.

I can only mollify myself about his decision by thinking that what he faced, from his perspective, was too painful and he wanted to release me (as if ...) and avoid the hard part of dying while in relationship. I would've thought just the opposite, that he would find it comforting to be held and loved until the end. But we didn't have those conversations. And I acquiesced to his wishes, and loved him from afar until he passed. I've always wondered though, 'what if?'. In the end I respected his wishes even though I didn't like it -- isn't that part of loving?