Final answer:
The most stressful aspect of treatment for infertility for the client and spouse is likely the emotional and psychological toll it takes on them, as well as the ethical issues related to costs and the status of unused embryos.
Step-by-step explanation:
The most stressful aspect of treatment for infertility for the client and spouse is likely the emotional and psychological toll it takes on them. Infertility can negatively impact a couple socially and psychologically, which can lead to marital friction or even divorce. In addition, ethical issues related to the costs of procedures and the status of embryos created through in vitro fertilization but not used for pregnancy can also contribute to the stress.