You just really evaluate the position that you are coming at this from. Do not be hasty to make either a rash decision nor put too much stock in the opinions of those on an online forum who don't know many of the details of your relationship. Yes, we can often offer a clear, objective and sobering point of view, but it's hard for us to understand all the intricacies of a long and complex human relationship via a short paragraph.
That being said, here's my (PERSONAL) two cents:
If you are coming from a position of weakness, AKA: i'm scared and worried she's going to leave me and couldn't take it if she dumped me so I want to do it first, then i would re-evaluate.
If you are coming from a position of power, AKA: I'm a high-value man and this girl is not meeting my needs as a man and is not putting as much into this relationship as I am, then...you STILL might need to re-evaluate. It's kinda a **** move to just flat out dump her without giving her a chance or explanation (not that girls never do this).
Do you think you would be able to simply dump her and walk away without being torn up about it? If so, then this tells me you are in a position of power and also that maybe you don't care as much about her as she does for you (which isn't always a bad thing).
The tricky part is that by the time you begin to see signs of a failing relationship it's usually much too late. Girls will often try to do everything to keep things right "on the surface" (such as texting that she loves you), all while the real signs of attraction start to cut out (not giving oral, not wanting to touch you or have sex as much) while she makes plans to jump ship or look for an opportunity to dump you.
However, the problem could just be that your sex life has stagnated and needs a kick start.
Thing of this as similar to something like a back injury (weird I know, but give me a chance here). Similar to how you wouldn't simply elect to have an expensive and potentially risky surgery at the first signs of back trouble. It's often much more wise to try more conservative approaches to fixing the problem... anti-inflammatories, physio, chiropractic work, steroid injections, opiates etc. before surgery. HOWEVER, if the situation is dire and the pain is extreme, then you may need to jump right into surgery to cut your losses and prevent the injury from causing irreversible damage.
Try a few things before you decide to dump her. Test the waters. Try to spice up your sex life: pin her against the wall in a semi-public place and bite her neck and pull her hair. Try things you havent tried before and really take your time warming her up and paying attention to her. Also, don't supplicate to her. Pull back slightly and judge her reactions. Withdraw your affection slightly and try to avoid falling into the "routine" that comes along with a relationship over a year long.
