OP you are so kind to even think of helping them pay for another round. Maybe like another poster suggested talk with your parents and see if you can pool money together and give it as a family offering. I would let them know in the meantime that you are sorry and thinking of them.

I am very sorry to hear about this.
We just found out that our first IVF did not work, and male factor is also an issue for us.
It hurt very badly in the beginning. I wanted to crawl into a deep hole and never wake up, but we have slowly begin to regroup and plan the next steps.
Maybe reach out to your SIL and let her know that you are thinking about them. It is hard for us to discuss with others, since nobody we know has struggled like this. It is very generous of you to help them with money. Can you converse via your mom? They are probably in a raw state now, so it may help to wait a little.

I just heard (from my mom) that my brother and his wife were unsuccessful with their first IVF. They could only afford one go and are devastated. My brother does not discuss things like this with me, though his wife has filled me in. (They live overseas.) I'm so upset for them. I don't know how to reach out to him because he is so uncomfortable with talking about anything even the slightest bit personal (we've never discussed their fertility issues, I only know because his wife told me), but I want him to know I'm thinking of them. Any thoughts on how to reach out or what I could do that would help? (I can offer them money but not enough for another attempt and I think he wouldn't be comfortable with that). To complicate matters it's male factor issues that have prevented them getting pregnant so far which I think may be compounding his inability to discuss it. They are apparently good candidates for another try.