The worst thing you can say to someone going through fertility treatment is to 'just try not to stress'. It implies their distress is a choice and that it might be contributing to the problem. Both ideas are more wrong than right, and together they create a loop that's genuinely exhausting to be caught in.
The stress-causes-infertility claim is much weaker than the cultural narrative suggests. Most well-controlled studies do not find that measured stress levels predict IVF outcome. What the literature does show is that untreated clinical depression and anxiety are associated with lower live-birth rates, but those are clinical conditions, not the ordinary anxiety of a difficult medical situation.
The distinction matters, and collapsing the two does real harm to the people going through this.
Grief is not a problem to solve. The emotional experience of fertility treatment is legitimately a grief response. Losses accumulate: the negative test, the failed cycle, the months that pass, the plans that get deferred. Acceptance-based approaches that work with the grief rather than trying to reframe it have better evidence behind them than positive thinking.
Telling yourself the outcome will be fine is not a coping strategy, it's a way of postponing the emotion until it arrives at a worse time.
Many people describe the emotional labour of fertility treatment as more exhausting than the physical. The social performance of being fine, the effort of concealing treatment at work, the decisions about how much to tell which people and when, these are real costs that add up over months and sometimes years.
The cognitive load article covers the practical dimension; the emotional version of it is at least as significant.
Couples cope in different ways and frequently misread each other's coping. One person throws themselves into research and information-gathering; the other needs to step away and not think about it for a few hours. Both are legitimate responses from different nervous systems, but without that understanding they can feel like withdrawal from a shared project.
Naming the difference, 'this is how I cope, not a sign I've stopped caring', is often more useful than trying to synchronise responses.
Something concrete to try
Most people going through fertility treatment are managing better than they give themselves credit for. If you're looking for something to do rather than something to feel differently about: regular moderate movement has consistent evidence for mood; a brief written acknowledgement of difficult feelings (three to five sentences, not analysed) has been shown to reduce rumination in controlled trials; limiting unstructured research time to a defined window rather than all evening reduces the loop.
If your distress is sustained and affecting your ability to function day to day, that is a clinical picture worth bringing to your GP, you don't need to be at crisis level for that conversation to be appropriate.