One might argue that the good sense of joy followed by love is evidence that when one loves someone, one is acting selfish [0], even though he/she might think otherwise.
[0]: People are rational and they wouldn't do things that don't result in more benefit to them than their cost.
Ah, but people do occasionally do seemingly-altruistic things, and by long experience, some of those are worth encouraging.
"Love" in English wears too many hats. C.S. Lewis' Four Loves does a good job explaining how the highest and best use of eros (which can be selfish) is to encourage agape (selfless love).
"The promise, made when I am in love and because I am in love, to be true to the beloved as long as I live, commits me to being true even if I cease to be in love."
I made that same exact argument in college to someone who was just trying to help me see how insane I was. Yes, it's slightly self-serving to love and find joy in love. But of all the forms of selfishness in existence, it's the most acceptable and least blamable one.
[0]: People are rational and they wouldn't do things that don't result in more benefit to them than their cost.