Boyfriend has a female work friend

A few months into his new job he mentioned his friend (let's name her Jessica). I thought nothing of it at first until a month or so later I noticed him snapchatting her and texting her as well... They have been best friends on Snapchat now with each other for the past few months (bumping me down to second). One time my boyfriend mentioned it when he opened up his Snapchat while I was watching and said, "look, Jessica and I are best friends on Snapchat now cuz you never snap me!" My boyfriend is someone who I 100% never ever think would cheat.  He is an amazing guy who I trust with my whole heart. But, when he receives a text or Snapchat from her he will turn his screen away from me or try to do it without me seeing it. I have no idea why he would do this except maybe that he doesn't want me to get upset from seeing her name pop up on his screen...? 

He will occasionally... very rarely speak about Jessica, and when he does he will either give as little information as possible at first, until I ask further: "I was with a coworker having drinks after work"..., or will tell me a platonic story about her in a way that makes it seem forced like he's telling me this story in order to make me feel like he has nothing to hide and to soothe me, but the way he says it with the awkwardness and forcedness makes me wonder if he has a crush on her or something. 

He has started sending more and more snaps to me in the past month out of the blue with no context (the amount of snaps is unlike him) and I believe she also receives these as well. (I've seen him send us the same snaps several times before). It hurts a bit because she is with him everyday at work and it seems she also communicates with him more outside of work than we do now... 

Lately I feel like my boyfriend has been pulling a way a bit, I have to put more effort Into communicating where we used to have ongoing text conversations all day... 

All I know is if this was another guy at work who he had hit it off with, this amount of outside of work contact would not be happening ... 

What I am most scared about is that in a few months, he and his team he works with will be constantly travelling around the country for the rest of the year. The thought of them being alone outside of work traveling together for weeks at a time scares me. I am not afraid of him cheating on me, but more so him maybe falling for her? Or possibly realizing there are other women out there who are better and breaking up with me. 

If they were just friends this wouldn't be an issue, but I am suspicious that there is more. 

He has assured me before that he loves me and they are both in relationships and she is just a friend, however I can't help but be hurt that he hides this friendship from me and I feel like an outsider looking in...

What are your thoughts on this? I would really appreciate anyone who has had a similar situation telling me what happened.