-Fe (alpha): This love is in essence, accepting somebody for who they are, while at the same time trying to uplift the person so that they become a better version of themselves. This can be interpreted by -Fi/+Fe types as manipulative, and that they are not really loved for who they are. It is not exempt from drama, and even insults.
-Fi (gamma): This type of love is the epitome of what is usually called "unconditional love". In greek the term is referred to as "Agape love". It simply means a reciprocity where you love, and are loved back, not judging the person. Unless you purposely do something to hurt the reciprocity, this love doesn't end.
+Fi (delta): This love can be referred to as "boundless love". It is empathy and psychological understanding towards all, but especially the object of your affection. It is conditional though, as this is also the element that 'tracks' transgression against what is right/good, and past certain point the holder may stop loving the other person.
+Fe (beta): This is romantic love, or 'Eros love'. What is commonly referred to as an 'emotional rollercoaster'. Unless it is backed up by some of the other types of love, it usually doesn't last unless it is rekindled.
They all can have varying strengths; you might love someone less or more according to these parameters.
IMHO, the most "fun" (and the most missed) is +Fe type of love.
These are in the order that I experienced them with my 4 'girlfriends'. Soon coming descriptions for the other elements (while I ruminate them a bit).