The emotional gamble - I need advice

My fiancé and I have been TTC for almost a year now with no luck. I am 48 and he is 42. We went for fertility testing and have been told that I only have 9 viable follicles. Doctor said we can try IUI but that it will be costly and with no guarantee. I have a daughter from a previous relationship but my fiancé has never had kids so I said to him that he has a choice - we can end it now and be friends and he can go and find someone younger to have a baby with or he has to accept that the daughter we share is the only one we will ever have.

One minute he says he’s going to stay with us, next minute he says not to think about it because we’re going to end up with the baby and then a few days later he needs time to make his decision ... all the while I feel like a yo-yo.

it’s not fair on me or my 7 year old daughter. I don’t want to go through months of shots and hormones and tests and disappointment, for him to just bail at the end when there is no baby.

have any of you been through these types of scenarios? can you give me any advice??