Online on Whatsapp after going to bed? Is he actually online?

My boyfriend and I are long distance (over 2 years together). We use Whatsapp to stay in touch when we're not physically together. Over the few days I've noticed that we'll be texting a bit and it will say he's online but there's no blue ticks. As if he's perhaps talking to someone else. He eventually does read the message and the ticks turn blue, then he'll reply at some point. We'd had issues with his ex a while back so I'm hoping it has nothing to do with her. And that maybe he's just not actually in our chat window when this happens. The first time this happened he was out for dinner with coworkers, I just found it odd that he was showing as online but not reading the messages as this hasn't happened before. Usually when he's online we're chatting back and forth no problem.

Today the same thing was happening and when I asked what he was doing he said he was reading a book. Eventually I told him I'd get back to work and he responded a minute later saying he was going to bed. But when I logged into Whatsapp after work he was showing as online. This would be around 3am his time and he's still showing as online now, around 5am his time. He is supposed to be working tomorrow SO I'm thinking that maybe he's fallen asleep and not came out of Whatsapp or something similar, otherwise he will be totally zombified. And he's a man who needs at least 9 hours sleep or he's like a bear with a sore head.

Is there any other reason it would show a person as being online if they're not? Perhaps some glitchy internet thing? Thanks.
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Now it says he was last seen at (5pm his time). So I'm not sure what's going on.
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+1 y
I casually mentioned it when we were chatting today and he said it wasn't him. I was still getting the 2 grey ticks for a while before they turned blue with him online so I'm a bit hmm. But when he said goodnight it didn't show him as online after. BUT I checked FB messenger and it says he was online 5 hours ago, 3am his time. Ugh.
Online on Whatsapp after going to bed? Is he actually online?
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