
I think that although she knew that Gosha loves her deeply, she wanted to show him the same love: that she was able to reciprocate it. Physical affection is just as important in a relationship to everything else and I suppose she just really wanted to experience a kiss with the man she loved the most, even if it meant her life

Yeah...it's actually not really that complicated to understand. You're right on the money...I wouldn't know myself and I especially don't claim to know the following...but. Supposedly. When two people fall deeply, madly in love with each other...they want to fulfil their wishes together, even at the cost of death.
Toki wanted to love Gosha the same way he loved her...it doesn't have anything to do about interspecies and all the other stuff...it was just a simply case of both a man and a woman in love. :]
Why? JUST WHY?? He wants to live a long live together as a family. But she just wants some stupid kiss. WHY WOULD YOU SACRIFICE YOUR FAMILY TO JUST A MERE KISS?.?!. WTF WRONG WITH YOU GURL (/TДT)/