A feeback loop is a process where output of a system at least partially is used as input to the same system to keep it running and to boost the output. The most common...and unfortunate...example is when echo from the output of a speaker enters a microphone to be put out by the same speaker to go into the microphone to repeat the process until the speaker overloads and everyone in range cringes. There are positive loops, however, where the process is either controlled or the capacity is limitless.
Today's Gospel illustrates such a positive loop. Our Lord tells His disciples that if they love Him and follow His instructions/commandments (output), then the Father in His love will send them the Spirit (input), which in turn bolsters the disciples' love and commitment (more output) with the Father continuing to bless the disciples with the assurance that their Lord is still with them (see today's Gospel reading for Mass here). God's capacity for love is limitless...after all, St. John writes in his first Epistle to the Church that God is love, after all. The Holy Spirit breathes that love into everything that the Spirit touches and infuses, so with every touch of the Spirit, if we persist in allowing the Spirit to work in us, our capacity to love expands as well, which spills over into love for God and love for those who bear His image.
The thing is we have to keep participating in the cycle. God will not force us against our will to participate, but will joyfully pour Himself out when we do. If we turn from Him and let our love wane and no longer heed the commandment to love Him and our neighbour, then the capacity diminishes, but if we turn back to Him, the cycle can begin again. For those of us who ebb and flow a lot, that can easily leave us stagnant and even spiritually lethargic, but for those of us who persist even through the rough times, through the emotionally dull or dark times, through the times when it seems He is not there, He still loves us and will still pour His love into us...if only we let Him.
It is not easy. Loving someone never is, which is the consummate irony. Our fallen natures, our old, entropy-plagued, and easily tired natures sometimes just get in the way. We get selfish, we lose our vision, we fall into apathy, and that itself is a negative feedback cycle. The challenge is (as in any relationship) to push past it, even though it seems insurmountable, even if it means taking it a day or even an hour or a minute at a time. Rest assured, however, that He is right beside you, waiting for you to turn and receive that love He so freely gives.