横恋慕[yokorenbo] illicit love
失恋[shitsuren] disappointed love
はつ恋[hatsukoi] first love
色恋[irokoi] sensual love
道ならぬ恋[michinaranukoi] illicit love affair

悲恋[hiren] blighted love
恋い初める[koisomeru] to begin to love
恋い忍ぶ[koishinobu] to live on love
恋慕う[koishitau] to miss