I resonate with the other PPers. Stay close to her and be there for her. You are her advocate and in time of birth she will feel and will be vulnerable (birth reminds us of our primal origins lol). Birth partners role is to be supportive and protective. Be her voice when she has none. Make sure that you have a copy of the birth plan on you at all times. (especially if you guys do have some things that you really really want to avoid or promote...ie skin to skin, or delayed cord clamping..sometimes in the euphoria of the labour and birth and the changeover of staff etc, wishes in the birth plan can be skipped without them needing to be).

One thing to remember is that you are an integral part of the birth journey. there have been countless studies done now that show that the birth partners (whether men or women!) also produce insane levels of the 'love hormone' oxtytocin during this time. sooo, to help achieve that: keep calm and carry on lol! oxytocin is inhibited by fear and adrenaline, so you two gotta get your calm on and a smile on your dial
naturally produced oxytocin is a wonderful thing, the baby loves the smell and helps with bonding for everyone.

HTH and goodluck with this amazing journey!