My SAE is frightend!

[Celox]

Dear Betta owners!

I'm a long time reader, but just recently an actual betta owner! I tried to get to know as much information I could about keeping bettas.

3 weeks ago I set up my 30 liter tank (8gallons) for my betta, added plants, etc. After 2 weeks of cycling I added a Siamese Algae Eater (and yes I'm sure its SAE and not CAE, I might be a first time betta owner but not a first time fish owner! I had guppy's before but I felt it was time to try something new, something challenging)
Now the SAE is a scared little fella, he's even scared of me after seeing me every day for a week (He stays completly still when I look at the aquarium and generally only comes out of his 'cave' - wich is actualy under a piece of driftwood where plants emerge from and close to the heater, a very dark spot where light is low)

Now I just introduced my betta to the tank, he's loving it! Exploring the place, and also.. meeting his new aquarium buddy!
I was Happy to see the betta did not show any hostile behaviour! He just went to take a look at the SAE, but the SAE is so nervous he instantly flees. Even if my betta is not even going towards him but is just taking a look at the heater, or swimming right by him.
Now an SAE is very very fast, and my betta is no match for him. So I'm quite certain he wouldn't be able to actually catch the SAE (my tank is quite heavily planted for hiding etc)
My question is, will my SAE ever calm down? (He does a great job keeping the tank algae and junk free, but I don't like seeing him so stressed)

I'm fascinated by betta's for a couple of months now, and had to resist the urge to buy him (I like doing research and looking at pictures of betta!). The day finally came today and I went to the local petstore, I wasn't looking for anything fancy just a betta that I would find attractive!

When I arrived at the store I saw 2 betta I liked, 2 red ones. I didn't even see the little friend I actually picked at that time!
When I was about to say 'I'm going to take the red one, could you gently scoop him out?' I saw my betta!
He's so pretty, his head is dark blue/black, his body fades from dark blue to blue and his bottom fins display a slight hint of red. But I could tell he was in a tank with other fish that nipped his fins, they were torn. At that moment I changed my mind and HAD to get this one

I'll add pictures soon