Does it make you mad when your significant other speaks to a friend of the opposite sex? I have male friends I speak to. Does it make you jealous?
No. Being the narcissist I am, my social media profile pictures are either pictures that were taken from shoots, or pictures in which the lighting fell just right and I happened to be wearing an extremely flattering outfit. So the "conversations" with which people of the opposite sex attempt to engage me are one way dialogues, all of which consist of:
15.01: Hi.
15.01 Hiiiiiii.
15.02. Hey.
15.02. R U there?
15.03. Why the fuck won't you talk to me?
15.05. I am deleting you.
(Apparently I'm supposed to be upset by that last comment.)
This is, of course, my fault. I don't have to accept these friend requests. I don't have to post sexy pictures of myself. I have considered deleting all of my social media accounts on many occasions. But I do have the rare experience of having an intelligent conversation with someone of the male persuasion, and no, my husband doesn't mind. We have open access to all of our social media accounts and I usually share the topics of the decent conversations with my husband anyway.
I've only dated bi people, them talking to someone at all is a risk. 
I find it easier to keep a significant other around by not freaking out about it. Falling into jealous patterns is more likely to make those sorts of insecurities come true. In one ex's case my not getting angry over her admitting to having a crush on a friend was why she decided to stay with me instead. Concern to a degree can show you care, but beyond a point (especially through repetition) it can become unattractive.