Ventadorn

"You've asked, my lords, for song" - as his lords are those who allow him room and board in their home, this is far more than a light-hearted request for entertainment at a festival. Rather, it is the demand of a supervisor, the work required to continue his stay. This makes another line, "Yet never sing for long," a little dangerous, as it appears that he is denying or working around their requirement. "I've lost the heart to try is an interesting play on words, as 'the heart to try' is a common saying, and not in the least bit romantic, more referring to 'heart' as bravery, fortitude, or strength of will. However, the 'heart' here has a double meaning outside of the saying it's in, as we learn throughout the poem that his loss of strength is based his romantic life, and he has indeed 'lost his heart' to a woman. The next two lines in this stanza suggest that his romantic life is going well, and his love is returned, yet he is still unhappy.
The next stanza explains why, for although he does not want for physical things, such as food, shelter, luxuries ("With gifts beyond compare/ my lord has honored me"), and although his love is faithfully returned, (next two lines), he cannot see the lady, as he does not dare to visit her, and so does not know how she fares. This immediately brings up the question of why he "dare not go there," which can possibly be assumed troubadour themes - she is married.
"Such joys I find" in merely thinking about her, that as long as he does so, he never even hears "if men shout or call." "So subtly does she snare/ my heart out of my breast" is another interesting depiction of love, as it is shown as theft, almost with malicious or malevolent intent, as snares are used to trap animals to be killed. The question then, on what she intends with his heart now that it has been captured. The next few lines describe the fact that though he is physically with others ("men swear and attest/ that they all see me here"), he thinks about her so often that his mind and soul are present not with them, but with her. Also, his "best part's still there," showing that he gave her the best of himself, perhaps this refers to his heart, perhaps his attention, perhaps something more, and now is missing that part without her.
"Shall we two live in strife?" Although often referring to conflict, here it appears that Ventadorn's 'strife' is more meant to refer to the inner turmoil of their souls, since they are so in pain without each other. Then he supposes that if he continues to live in that pain he will die. Almost pleading for her to take him, though not directly addressing her, he hints that his pain will end if "my Lady might/ receive me in that place" and allow him to sleep with her. "Smooth and white" shows some of the concepts of beauty at that time.
"Troubles or love's pains" is a possible invoking of that bittersweet eros theme found in so much love poetry. Then it becomes clear that the gifts he truly values the ones which God gave, are love. When He gave freely, Ventadorn "took my gains./ Now when his gifts abate,/ I'll suffer that as much." He then says that in current society, he cannot travel to see her and must wait. I'm not sure if this is possibly referring to society looking down on adultery or the lack of appropriate travelling methods or even his inability to leave the castle for a while and keep his job.
He then thanks the Lady for her love though nothing can come of it now, and swears that he loves her more "than all past loves of mine," showing again the drama of these troubadour poets. As he bows, love shown as slavery or subjugation is shown again, since he submits himself to her and, "yielding myself to you," to her control. He then says that all he would ask of her is "one sweet glance/ If sometime you've got the chance." Whether he means that she should physically visit him, or merely that she might pay him more attention (write him more letters?) is a little unclear.
He then says that he and his friend Escudor are going to wander, possibly to distract from love's pain, and asks for God's blessing. Ventadorn also says "He'll bring what he can find/ To keep him company" presuming that he will find women on the road, while as for Ventadorn, "My Magnet goes with me." This is an odd way to refer to his love, as a Magnet. Perhaps because she serves as a direction to his life, and he cannot leave her, nor she him, so they are attached in that way through their love, if not physically. It's an odd metaphor.