Advice on relationship

I am just concerned with his sudden coldness. He is not using emojis anymore, his replies are short, and today, he told me he is having lunch in 15 minutes (Swiss time) while it was 11 am in UK for me. 

Doesn't it sound a little mean? 

I already texted him, saying "I've noticed outer conversations have been shorter than usual. Is everything okay between us?"

I agree, which is why I think you have to word that question (if you choose to ask it at all) carefully as you have rightly described. It's hard to judge how to approach this properly as everyone is different, but I think you should try to think about why you are still interested and how to express it in text. It might get him to open up about the things he still finds interesting about you.

However,if I am going to ask him why he is not interested anymore, I will come off as desperate and clingy, which will turn him off. That is not my intention at all.

Thank you so much! 

I really appreciate your advices. Although I want to text him right now asking if something is wrong, I'd wait a little bit. I don't want to think negative. 

He always told me that I should understand his communication style because he has to deal with things. 

I understand his perspective. I don't want to rush him to reply to me. When I have something on my mind, I text him without any expectations from him to respond to me quickly.

We only text at the moment. We even discussed about doing video calls, but we are not ready yet. 

Yeah, I get what you mean don't worry. That's in my experience, a very common experience of people on the spectrum. I have been told I have been very blunt in the past, so take my perspective with a grain of salt, but like I said I prefer tackling the problem directly. 

It's always very difficult putting your trust in other people when that trust has been taken advantage of. Try to let him explain his perspective as best you can without interruption, and listen intently to what he says. A lot of guys don't tend to open up fully to other people, so try to reassure him if it seems like he's not being fully honest with you. He's not being a hypocrite, he just doesn't want to put his heart out for someone that won't understand. (not an accusation at all btw)

Have you not talked about doing video calls or do you think that will be worse?

Maybe I can wait until tonight. We are going to switch to another app because the app we are now using is more visible. He said that other people may have a glance on our chat from his laptop.

I usually feel anxious about many things, to the point where I create the worst scenarios in my head. 

We haven't seen each other in 3 years. I told him I planned to visit Switzerland one day. And if I like, I will keep going. 

I asked about trust, if he still trusts me. He replied that so far yes, but some of his friends betrayed him. So he has some trust issues.

Like I said, it feels like the vast majority of what you have brought up are things you should approach him with when the opportunity presents itself. Try to have a longer chat than normal on a day where you both have the time to say your thoughts in full, and make your decision from there. The longer you leave it, the worse you will feel. 

Is there anything stopping you from sending a text to ask how he feels? 

As you said earlier, he is also really busy. He goes through some hard times, looking for a job and sorting out paperwork. 

Also, I only lied to him last week. I never ever lied to him during our 4 years of friendship. 

He mentioned to me one day that we are not yet boyfriend and girlfriend when he explained to me what a certain word means. I found explanations of that word, one of them is that it is an endearment thing.

Communication is *always* what you need to keep relationships going. Ask yourself this: If he is already getting suspicious that you are lying to him two months into your relationship, is this someone you can truly be open with in five years? Ten, even? 

It is plausible that he is busy with work and doesn't have as much time as he used to for chatting with you. Maybe he doesn't see how the lack of Emojis affects you emotionally. It's always best to talk these things through as soon as you notice problems so they can be resolved without leaving hard feelings behind. 

Here's one more thing to think about: What do you have to lose by asking him where he stands with you? It would of course, hurt, if he said he was no longer interested in you but you would be able to move on without that uncertainity weighing you down. But if that is the worst case scenario, do you truly have anything to fear?