Welcome CautiousHope! That is a great name and it sounds like you are approaching things just that way-
Please do check out the stickies as they provide a lot of helpful insight-
What others have said here I cannot agree more-and to answer your question
Are the constantly swinging highs and lows to be expected?
There are a lot of expected highs and lows I believe in anyone-but yes A's dealing with recovery can be especially high and low-they are dealing with a lot and it is all on a new level of unfamiliar feelings they have not felt because they were numb. Just like someone who is Co-dependent, or many other's. When we start to peel that onion and the layers come off the highs and lows are unexpected to us-and so it will be to others.
It appears you are a great friend for sticking by and I believe that what he said about learning to love himself again before he can love someone else is so true! I had to learn how to love myself again and everyday I still have to remind myself that I'am a work in progress.
Hang in there and if it is meant to be it will be!
Welcome again!