It's gruelling because you take months/years saving for it, cutting back on things like holidays. You start to put life on hold (not booking holidays, not changing shitty jobs in case you're pregnant etc). You decide you need to be 'healthy' to give it your best shot, so you start buying and taking loads of vitamins, acupuncture, reflexology etc, so you have even less money. It takes months and months to get the starting appointment lined up, by the time you've gone through all the blood tests and scans. Then they might start testing your partner. Finally, you're ready to start injections.
An average ivf cycle has 8 to 9 appointments. Other than the first one, you don't really get much notice as it all depends on how your cycle goes, so generally you'll have to tell work what's happening. They'll start you on 'the Mummy track' immediately, even though the chances of the ivf working are slim. So you have no privacy, no cards to your chest.
During the cycle you're exhausted. The injections and side effects are horrible. It feels like you're carrying two coconuts.
And then you become aware of all the obstacles. Your ovaries might not develop any follicles. Your follicles might mature suddenly or release the eggs. The trigger injection which makes you ovulate might be mistimed. The follicles might be empty. The eggs retrieved might be immature and not fertilise. The sperm might turn out to have penetration issues, so the eggs were wasted. If you have any that fertilise, then you're into the hunger games, so the embryos might arrest before day 5. Get to day 5, and they have to be a good enough quality to freeze or transfer. If you're using frozen embryos, they have to survive the defrost. Your lining has to be the right thickness for transfer. After transfer, you have the two week wait before you know if you're pregnant. During that time, you'll be anxious that something you've done might stop an embryo implanting.
And then you might get a negative result. You may as well have thrown thousands of pounds away. Then you're doctor says I think next time we could improve your results by doing x, y, z.... You wonder how quickly you can save more money for another cycle, what else can be cut back.
It's awful.