I think the friends with benefits situation is only for people that are are absolutely certain that they will never get attached emotionally or jealous of whomever they form that kind of relationship with. All parties involved must be absolutely sure that is what they really want and know what they are getting themselves into. And also aware of what consequences there are before just jumping into something like this.
The Friends with Benefits type of situation is not for everyone. Make sure you are clear to the other person and that you both know for certain if this is what you really want and that nobody had lied to anyone or had mislead anyone from the beginning.
If you have any doubts about it, then it's probably not something to get into or get involved with. Otherwise, you could end up an emotional mess later or that they can, or eventually the both of you are in a mess.
Friends like their friends and it is friends with benefits. Just remamber, somtimes having sex with your friend can screw up the whole friendship. Make sure you want to risk that before you do it. You may think it's no big deal, but trust me, it is. Now, why do I say this. I actually experienced it. It was good for a brief time. We are no longer friends. It wasn't just one thing. It changed the whole dynamic of your friendship. I miss my friend, but it's over. I wish I had never done it. I'm not saying your experience will end the same. But, is it worth the risk of losing your friendship? There are other men to meet and have sex with. I hope it all works out for you whichever way you go.
If you both have feelings for eachother then yes, as it could blossom into something more. However if only one of you has feelings, you'll be hurt when the other wants to break it off or doesn't show feelings back
If it's a one sided crush it's a really bad idea since the person may just be interested in the benifits and you will definitely catch feelings If you are friends either one of you will develop feelings (thanks to pheremones)