Hi, I just joined the forum and weirdly just before I joined (your post is the first I've read!) I was reading an article which might go someway towards explaining their behaviour.
I should also say, you have said you feel like you're losing your best friend but you have said 'My BF' and also posted it in the spouses/ partner section which makes it quite hard to tell if he is your boyfriend or best friend!
Either way, the article I was reading (which is here:
www.additudemag.com/slideshows/adhd-emotions-understanding-intense-feelings/) Explains that people with ADHD are more likely to have social anxiety, largely because they have 'Rejection Sensitive Dysphoria' - which basically means a person has an unwarranted and exaggerated fear of rejection and being seen as 'uncool' or '
Regardless as to whether he is your boyfriend or best friend, it sounds like he has opened up to you a lot - and I would guess to a much more significant extent than he does with most people.
So basically you've shared some emotional moments and probably know him very well.
The article also explains that people with 'Rejection Sensitive Dysphoria' - which, as we have already established, is very common with people with ADHD - often become people pleasers. They want to behave in a certain way, talk in a certain way that limits the chances of them being rejected by peers.
I have definitely been a people pleaser all my life and I was aware of it too, and when I was with my ex-girlfriend at Uni I really hated being seen with her by mutual friends. Not because she was unattarctive, in fact she's one of the most beautiful people I've seen, and not because she is intolerable to be around, she is lovely and a delight to be around, but because I could not work out how I should be acting.
I am a very sensitive guy and can be very cute and emotional all the time. So when I would see mutual friends, especially if they were male, I wouldn't know how to act 'masculine' in front of the friend, so I would not be rejected by them, but also act myself in front of my ex.
Add in the fact ADHD can make it very difficult to keep up with someone's pace and fully process everything, then I was having delayed reactions to what they would both be saying whilst also struggling to process in my mind how I should be acting right now and what I should or shouldn't say . On top of that, perhaps more than anything, the fact my ex was the one person in the world I couldn't bear to lose meant I couldn't bear to be seen to be awkward for fear she would leave me.
This led to some awkward situations in which I would mumble, look like a 'deer caught in the headlights' like you just said - and I am ashamed to say that when my ex would go out clubbing with her friends and tell me they were coming over in 5 minutes, I literally ran out of the flat straight to the library to do Uni work instead!
So it's possible his sensitivity to rejection, need to please others, and struggle to process conversation, causes him to panic and flee because his brain can't process what to do.
It should be said, although I am a 'people pleaser' with those I am not comfortable with - around my ex I was able to behave like myself all the time and felt fine (apart from the first 6 months anyway!!!). I also had much less trouble processing what she would say to me and keeping upw ith conversation when we were alone together because I was relaxed.
All I would say about it is my ex did also tell me that mutual friends felt I didn;t like them because I wasn't saying much and she did also point out to me when I would seem uncomfortable. There was a time when we were at the bowling alley and she was annihilating me (I have dyspraxia so my coordination is terrible and I struggle with stuff like this) and because the people playing next to us were alpha looking males I became very quiet and started to look uncomfortable.
As soon as she said to me "Are you OK, you seem really awkard and uncomfortable" I panicked even more and we had to leave the bowling alley mid way through the game!
So I would recommend not letting him now how awkward he is or letting him know how obvious it comes across because that would just make him panic more. But he probably knows its akward to - and he knows he previously behaved awkwardly - which makes it extra extra awkward when it happens again!
I hope I have made sense because I am very tired and emotionally exhausted right now! And I should also say I am basing a lot of these assumptions off of my own experiences and how the article related to them. It is possible something else is going on. I guess it kind of depends on how he interacts with his workers whist you're there on a day to day basis? If you're job doesn't involve much 'on the job interaction' because you're constantly busy and no one ever gets any time for chit chat, then after work he is not wanting to be around you at the same time as being around others, well then what I've said might go some way towards explaining it!
Either way, I hope you guys carry on getting on well and if he is being panicky in the same way I have, do not feel worried at all. It is not you that is the problem, it is his brains wiring and I'd be certain he knows it as well in the same way I did, and that he feels ridiculous about it too, which is why it's easier for him to play dumb!