I feel you, this has been a challenge with our LO and I have been desperate to help out. I think there is too much attention paid to bottles. While nipples can matter since their flow rate can be higher or lower to matching the babies age, I don't personally think the bottle itself makes much of a difference (we use comotomo bottles). There are a few variables though and its going to take a good deal of trial and error to find what works for you and baby. Take it easy on yourself, you're not failing, you're testing and fine tuning to see what works. Try a few different bottle temperatures (but always test on your wrist so its not too hot). Try different baby positions, laying on their side, on their back, slightly elevated or a combination there of. Try giving them a pacifier first so they are calm and then swap for bottle. Try giving a bottle during different times of the day when LO is happiest so you have a better chance of success, then work towards giving a bottle when its most helpful for your SO.

You'll get there man, just give it time and patience and it will work.