How we cite our quotes:
Now counting best to be with you alone, (7)
Here, once again, we don't see jealousy itself, but the preconditions for jealousy. If the speaker treats his decision to "be with you alone" as a matter of "counting" the pros and cons, he must not have a very profound relationship with "you" in the first place. And if the relationship is not profound, there won't be the confidence that could protect against jealousy, right?
Then bettered that the world may see my pleasure; (8)
Here, once again, we see some of the underlying causes of the speaker's jealousy. Think about it: if you want to show your significant other off to the world, you're not doing it because you want people to think that he or she is ugly, right? But if your significant other is attractive, doesn't showing him or her off make it likely that other people will find him or her attractive too? And doesn't that raise the possibility that someone might steal that person away from you? Even if this doesn't actually happen, the seeds of jealousy are clearly being planted. We can see where the speaker's neurotic doubt is coming from.
Sometime all full with feasting on your sight,
And by and by clean starvèd for a look;
Possessing or pursuing no delight
Save what is had or must from you be took. (9-12)
As we have mentioned elsewhere in this module, these lines seem to show the source of many of the speaker's underlying problems. Especially in lines 11-12, we get the sense that things might not really be going so well between the speaker and his beloved. If so, this could give rise to the lack of trust that ultimately results in the speaker's feelings of jealousy.