This site and the forum is great and you will get much of the info you might need, IF your lovely one is presenting 'normally' and that may not be the case.
It will depend on your relationship, but there is that awkward/embarrassed/guilt felt by both sides if the non-diabetics tries to 'help' by for example buying what they perceive is a good (alternative) to something they used to like/eat/drink frequently. My idea of low carb vs my husband's is very different, and having to explain why the 'skinny' hot chocolate he bought me for Christmas was not 'suitable' for my way of controlling my blood sugar was horrible for both of us. So unless they specifically ask you to search for an alternative, don't!
There is also a very fine line between 'appearing disinterested' and leaving someone alone, and on the flip side, not letting them feel 'normal' and going on about diabetes when they are trying for 2 seconds to think about something else for a change!
I'd be honest, and ask which approach they would like, pro-active support, or silent supporter; until you both get into a new routine with all the knowledge you need to deal with things, it will be hit and miss. But do read all you can, so that you can support an offer knowledge when needed.
Good luck to you both, those early days are hard, so don't beat yourself up for not being an instant endocrinologist!