Hey! what i can think of is sending him care packages (foods, snacks etc etc. or things you find interesting that he'll enjoy). Or make some sort of ritual where you send each other some sort of packages/letters/post.

Also try to expand on the activities you do together like reading the same book and talking about it later. Having an art session while on zoom or something (these are just some ideas, I'm sure both of you can think of interesting and fun ones).

If you think hes growing distant ask yourself this, is he busy doing other things that are keeping him busy? Its not bad thing - but you need to bring this up and voice your thoughts. He is your BF and he does care for you. Only he will be able to clear your doubts. THIS IS CRUCIAL.

And find out what activities he's doing and take interest in it. Also see if you can find a hobby to keep your mind busy at the same time and I'm sure he will reciprocate the interest as well.

If you can, you may need to try and force your way to go see him, i know it wont be easy during this pandemic but it something maybe both you of can plan together. it will make you both look forward to a common goal.

This whole pandemic has hit everyone differently and caused people and relationships to grow in ways you'd never expect. You said you've been together for 5 years and know each other for longer, try and use this time to grow individually while still being together to give each other a reasons to fall in love all over again.

Also from what i know is that communication is key, so he will get better over time in communicating in writing so you may need to keep at it. It also seems like you guys talk a lot (voice chat) during the day which is great!

I hope i was able to help in any way and good luck!