Just some thoughts...
It's normal to find someone more attractive than your bf (or gf...
it applies both ways). The issue here is for you to remember,
you've made a commitment at some point in time. It doesn't matter
when, but since you've made it, you've got to work at it.
Talk to your bf about your crushes, talk about your insecurities,
talk about how you feel, and it's best to talk as soon as the
problem arises. That way, things get brought out and can get
resolved sooner rather than later.
About your problem, realise that there's so much more than just
"things we have in common" in a relationship. I just got engaged to
someone who doesn't share many things in common with me, but I know
I can trust her and that she'll be there for me. Friends who share
common interests will come and go, and likewise, your interests
will change and you can't possibly change partners just because you
change interests.
Cheers
