Relationships

There comes a time in a relationship where the spark is gone.  It's happening to me now.
I don't know where it has come from, but I have been increasingly unhappy.  Maybe it is work, maybe it's the fact that my boyfriend is no longer funny and amusing, maybe it's because we are both working mad hours and never see each other.  Whatever the reason, it's an unsatisfied feeling rather than one of my down in the dumps moods.  And I have been feeling like this for a while.
But I don't know how to begin ending the relationship.  It just seems overwhelming no matter how I think about it.  I know I will have the freedom to work my summers in the UK and winters in this ski resort how I have longed for for years now.  But am I giving up a lot?  The unconditional love and support of a partner.  Do I just use him for support and not give anything back?  I have no enthusiasm to any more, I know that much.  I'm giving up the roots I have put down in a lonely town.  My cat (done that before).  And I know he loves me and I don't want him to go through what I have experienced when someone you love leaves you.  So I stay put, look for the positives (every day I look for the positives but find them hard to find).  I feel so lonely right now.  I miss my friends.  I miss my past life.  Maybe I have rose tinted glasses.