The song is about loving two people at once. One you are in love with one you love. 'I won't run into you'....they don't want to make that decision or be tempted. They are at home, but not at home Bc they are not with the person they are truly in love with and meant for. They are using THAT person's instruments. They thought they were in love but the old love shows them this 'home' and love is not real, meant to be, passionate 'in love'. Hence, why they don't want to run into the reminder that their current situation is not true happiness.
The song is about loving two people at once. One you are in love with one you love. 'I won't run into you'....they don't want to make that decision or be tempted. They are at home, but not at home Bc they are not with the person they are truly in love with and meant for. They are using THAT person's instruments. They thought they were in love but the old love shows them this 'home' and love is not real, meant to be, passionate 'in love'. Hence, why they don't want to run into the reminder that their current situation is not true happiness.
Or so I feel... =)