You can not know another sentient being so well and not love them. It is a well acknowledged fact.
Masters love their padawans, padawans love their masters. Crechemates love their crechemates. Everyone loves their friends. Contrary to popular opinion, love among the jedi is not forbidden.
The reason is this:
From very early on, every one of them are taught to put the will of the Force before all else. There is no danger of conflict when both parties agree that the Force is more important than either of their lives.
Only it doesn't always work.
Some jedi forget themselves in their emotions. Grief, jealousy, rage, fear, possession; jedi who know love must inevitably know the other.
Qui-gon knows them better than most because, while he loved Tahl with all the simple dedication life in the jedi order accords, he has recently realized that he is actively in love with his apprentice, Obi-wan Kenobi.
Love like this has occurred within the ranks many times before but, unlike the other kind, it is discouraged.
The reason is this:
Qui-gon knows one of them will die in this battle. He does not consult the Force to see who should die, but instead decides.
He has lived the last several years of his life hiding his secret, letting it ripple beneath the surface of his mind and coil around his heart. He has remained silent, he has refused to act (to touch, to kiss, to take) but this – this is beyond his power to give.
To him, Obi-wan's life is more important that the Force.
He rushes ahead, he does not wait; he lies on the cold metal floor as his beloved padawan fights and defeats the first known Sith in over a thousand years.
Cradled in his apprentice's strong embrace, he is shocked to see tears. Obi-wan never cries. He fills the silence with entreaties to train the boy, now deliberately swallowing the words he has waited to say for so long. He refuses to compound the sadness of his companion.
ILoveYouILoveYouILoveYouILoveYou
His eyes close, his heart stops, his mind echoes with the words he will not say.