A good friend is always going to be supportive of your relationship and be there for you when things don’t follow through the way you want them to. On the other hand, sometimes a friend acts a little peculiar, or is there for your partner in times of need more than they are for you.

There are a few ways to tell if your friend is trying to steal away your significant other, if you suspect they may be pining for their affection. Better yet, there are always ways to thwart their progress and remind them of who is dating who.
One way to tell what their intentions are is to, first and foremost, listen to your partner. If your partner loves and trusts you, then they will likely report back to you of any questionable things done or said by your friend. Feel free to approach the issue with both parties in a diplomatic and mature manner. It never hurts to try and talk things out before jumping to any wild assumptions or letting things fester quietly.
It may not exactly be flirtations, either, that your friend throws toward your partner. Sometimes, it’s a little more subtle. There are certain things to look for, if you suspect your friend may be interested. For instance, does your friend always want to talk about them? Does your friend give you questionable advice for your relationship that may later backfire? Does your friend seem to side more often than not with your significant other when an argument arises between the two of you? And is your friend there at the weak points of your union to help your partner rather than you? Or perhaps they say they’re helping your partner for you.
Either way, whether subtle or direct, if you sense their motives are to try and injure your relationship for their own personal gain, the best thing you can do is talk to them about it. Depending on the compatibility of personalities and attitudes, you may be able to grab your partner and friend and talk to them together in a three-way conversation. If you talk things out, but the behavior still continues, you may want to consider distancing yourself and your lover from that not-so-great friend. Give things some time to boil over during that period and see how things go on down the line.
If you find that your friend continues to disrespect you, or that their previous behavior has worsened, then it may be time to just ignore that friend permanently. Some people just don’t learn, and sometimes they just never will. No good would come out keeping negative energy around you and your relationship. Be aware that all a friend like that does is wish for you to fail so they can reap the rewards of their long-term discouragement. The bottom line is that regardless of who that friend may have been before, they are no longer a friend to you.

Never lose him