From what I believe, that relationship "like many relationship" seems to have been stagnant all through the three years at what I like to call the "growth stage" (read down to see the what I mean by that).
By the way, I love your stand on love because that's the winning attitude that guarantees true love.
Personally, I believe the mistake most people make with love is to believe and treat TRUE love as just an EMOTION! Yes, love is an emotion, that's a FACT!
But to me, true love (the type that will last forever, the type that will sustain a relationship till death) is much more than just an emotion but rather a DECISION, and that's the TRUTH.
The emotional stage I believe is the "growth stage", while the actual "maturity stage" of a true love is the decision stage.
I believe, if you don't make a solid decision to love someone forever irrespective of situation and circumstances, that love might not be able to withstand the trouble times (because every true love relationship must experience it).