Sadly 'love' is rarely unconditional though I understand what you mean. I've found it helps to accept that most things are finite and as such I try to cherish them in the moment that they are there/offered, but not hold ill will or bad thoughts when they dissipate or things go sour. I don't know if that helps, but there are often those around us who come and go, but help and love is often there... it just changes hands.