My godfather has been my mother's best friend since they were eight  years old, and they are still best friends today. My father (and my  mother's husband) accepts their friendship. My paternal grandfather and  my godfather are also pretty cool. Of course, my maternal family knows  him and they're cool with him as well. My father is a deacon, and is in  constant communication with female members of his church. Again,  platonic friends. Being around parents who have a mutual understanding  that they can have friends of the opposite sex, it floored me to date a  guy who pretty much wanted me to abandon the few male friends that I  have. 
Boyfriend started off pretty cool. We hung out regularly, talked on the phone daily, and could chat about anything. I thought  this was the perfect relationship (and being as commitment phobic as I  am, that's pretty big) up until one day when I told him a male friend of  mine was going to come by and see my new apartment. I'd never seen  someone change their whole personality so quickly. For the rest of that  week, I heard constant spiteful comments about how my "date" was coming  on Saturday. The day that one of my male friends came by, Boyfriend  called from an unidentified number and hung up on my answering machine.  The next day, he bombarded me with questions about what time did Friend  get there, what time did Friend leave, and what did Friend and I do  while we were hanging out. I almost felt like I was in an interrogation  room. Considering that I'm not the jealous type, I didn't understand his  frustration nor do I to this day. From that relationship, I learned  some very valuable lessons. 
    Lesson Number One: If you're going to be in a relationship with  a jealous person, make sure that you introduce him to your friends. He  may feel more comfortable if he knows who your other friends are instead  of a mysterious friend showing up out of the clear blue sky. On my  living room wall, I have several pictures of guy friends I've had over  the years. Thinking that was hint enough that I hang with guys more than  women, I assumed Boyfriend would understand. Although Friend and I had  been tight for 10 years, it didn't occur to me to introduce Boyfriend to  Friend because I didn't think it was a big deal, but afterwards, it seemed like a reasonable thing to do. 
 
Lesson Number Two: To avoid possible accusations that you and  your opposite sex friend are messing around, try to include your  significant other in hanging out. Even better, if Friend is involved  with someone, invite him/her along too. Double dates aren't really my  thing, but it keeps the peace and again isn't unreasonable. It also  gives Friend and Boyfriend the opportunity to bond. I see my godfather  and father hang out, laugh, and chill when he comes into town to visit.  My godfather even stood in my parents' wedding. Had my father and my  godfather not gotten along, that would've never happened. 
 
Lesson Number Three: Set a time limit on when your opposite sex  friends can call. I'm a serious night owl and my guy friends know it. I  was once on the phone with Boyfriend, and another guy friend from college  called me pretty late at night. I answered my cell phone while I was on  the house phone with Boyfriend, and Boyfriend could hear my whole  conversation. I didn't put him on hold or the phone on mute because the  conversation was brief and friendly, plus I had nothing to hide.  Boyfriend misinterpreted the conversation as some type of booty call.  Where he got that idea, I have no clue, but that was when I started to  realize he was slightly possessive. After ignoring his rants for a few  minutes with yawns and changing the subject, I finally got him to admit  that he felt it was odd that another guy would call me so late. Even as a  night owl like me, he still found it fishy. I shrugged and told my guy  friends to try to call me at a more reasonable time, say before 10 p.m. 
   Lesson Number Four: If your opposite sex friend does call,  please ask Friend to introduce himself to Boyfriend. I learned that the  hard way with my godfather's wife. I called his house  one day and asked to speak to him. Now mind you, when I was younger,  this was never an issue. But as a young lady grows, her voice becomes  more mature. My godfather's wife hissed about me stating my identity and  when I told her who I was, she complained about how I could've spoken  to her before asking for my godfather. At the time, I didn't understand  the harm, but had she spoken to me in a calmer tone, I'd have understood  why it is important to keep the significant other at ease. How much  effort does it take to say "Hey ____________, this is ____________. How  are you doing? Can I speak to _________________?" This way, the  Significant Other knows who is calling on the phone for their  Significant Other, and it could possibly keep Friend and Significant  Other at ease. 
 
Lesson Number Five: If Significant Other wants you to give up  your friends now that he or she is in the picture, personally I don't  feel this is justifiable. Friend could've been there before your  relationship started and will be there if/when your relationship ends.  Even when my godfather's wife had an issue with me calling and not  speaking to her, he didn't stop being friends with my mother nor did the  relationship between us become any less tight. His wife accepted that,  and although she and I are not in communication now, the bond stayed the  same. To give up a true friendship for someone else's insecurities is  not only unfair to that Friend, but it's not fair to yourself.  Friendships are few and far between, and if you luck out enough to find a  genuine friend, don't let that person go. If you are faced with an  ultimatum like this, ask your Significant Other if they like you for  you. If they do, then they should be able to accept the package that  comes with you, friends included. And if they don't, then Significant  Other needs to be with someone just like him/her. There are those who  enjoy Significant Others who should have side jobs  as police officers, and then there are those like me who don't have the  time nor patience to humor someone else's jealousy and insecurities.  Walk to your door, open it, and kindly let Significant Other walk out.  After all that explaining, it's really not worth the trouble. Hell, if  you're lucky, Friend will introduce you to someone less psychotic.