<human>: Can you summarize the given text in a few sentences?

Alright, new to writing to reddit as I've always just kind of browsed but I figured why not just write about this since its been on my mind a lot. Also, I'm on mobile so don't mind the mistakes. I (24 M) with (22 F) am currently in a relationship that I have been in for almost 4.5 years and we have only broke up once but lately it either seems like we or mainly me, has lost the spark for what once kept us going. We've had our problems with communication where I was communicating more for the both of us where she would not say much about her life, problems in the relationship until she had a few drinks and found the courage to do so.  She has made her improvements but I am wondering if it is too little too late as I am sometimes finding myself withdrawn or distant from the relationship. Honestly, we could have broken up a few other times but I chose to continue the relationship and I'm not sure if its because I'm too complacent or just settling because we've been together for so long and have such a history. 

    Now this alone could confuse anyone but I have recently developed a crush on a coworker and I found out she may feel the same or at least has noticed me for my good qualities. I wouldn't go and try something with her for the sake of my relationship and would not want to end one long term thing to immediately start another but I do find myself drawn to my coworker. 
 My question has to do with loving someone and really wanting to develop a strong future with someone. I don't tend to think too far ahead as I like to focus on the present but if I don't see a future with wedding bells and kids with my current relationship, is it wrong to feel like we have an expiration date? Sorry for the random rambling and being all over the place but the thoughts are just pouring out right now.
<bot>: 4.5 year relationship and not sure as to what type of future we will have, also developed a crush on a coworker and found myself even more confused.