I don't mind some analysing, because it really can be helpful if someone says, "Well, I was in a similar situation with my sister, so maybe your cousin would respond well to X.." But like MsJWine and others have said, it can get out of hand when it's just *announced* what it's about.
The control thing comes up a lot, also implying posters' relationships are unhealthy/abusive. Things like, 'you should reevaluate your relationship' based on one side comment. For example, something like this I think would be jumping to conclusions:
Poster: My boyfriend really gets irritated when I hang out with a particular friend--he's never told me not to, but he rolls his eyes and is obviously aggravated. He never does this with any other friend, though.
Response: He's manipulating you to isolate you from your friends! This is a classic sign of an abusive relationship, and you should leave the jerk!
But, this would be more OK;
Response: Sounds pretty passive-aggressive; have you asked him straight out why he doesn't like that particular friend? Maybe he thinks you spend too much time with them at the expense of the relationship, or maybe something about them rubs him the wrong way. He could be trying to manipulate you to avoid that friend, or maybe he just can't keep his aggravation to himself even though he knows he doesn't have the right to tell you not to.
Response: My ex-boyfriend started doing that with one particular friend; in his case it was definitely a manipulation technique--does he also cut down other activities you do without him? Or do you think it's more that he really dislikes that friend?
And if the OP responds that, no, her boyfriend is perfectly fine when she goes out for various things without him, the response isn't to keep hammering on the topic but to go, 'oh, looks like it's not the same situation'. I think it's natural to assume that a situation that looks the same might have the same causes, but insisting it must be is frustrating.