<human>: Can you condense the text into a few key points?

I know this post may sound selfish but screw it. So there are 5 of us in this group of friends and the one that we are all bothered/worried about lets call him Tom. Over this last summer in order to broaden our horizons as a group introduced various characters to our group. Too keep a long story short one of my good friends, lets call her Jane, latched onto Tom in a completely platonic way. Tom has a girlfriend so this is confirmed. 

Since the summer they have grown a lot closer. They stopped only hanging out with each other when they are with the group and they aren't shy about being each others best friends around us. Tom has started keeping secrets from the group and would rather share things with Jane rather than the rest of the group. Tom constantly puts Jane ahead of us and I'm pretty sure Tom has talked about us, not sure bad or good, to Jane. And I'm pretty sure Tom would chose Jane over any of us in a heartbeat. 

In short I'm asking what should I or the rest of us do? Confront him? or let it be because we are all separating (for college) soon? Any help will be appreciated.
<bot>: I am in a Group of best friends, we introduce one of them to someone new, he latches on to the new person and we are all kinda bothered by his new "bestfriendship"