1. grief: sorrow.

3. That she hath thee, is of my wailing chief: the chief cause of my wailing is that she has you. —As the next line makes clear the poet values the fair young man much more than the lady that they are both involved with.

5. Loving offenders: —The poet is addressing both the fair young man and the lady that they are both involved with.

12. cross: emotional burden.

14. Sweet flattery!: —I believe that this shows that the poet knows he is fooling himself.