<human>: Could you distill the essence of the text into 1-3 sentences?

Me, F/21. Him, M/23. Been together just over 2 years. This is not my first relationship, but it is my first ltr/serious relationship. 

First off, he is a great guy. He is kind and trustworthy. I feel lucky to have met him.

But lately I have been feeling unsure about our relationship. I don't feel attracted to him and this is becoming apparent both inside and outside of the bedroom. 

At the beginning of out relationship I was extremely attracted to him. We started dating only a month after we first met and he seemed to me to be a very confident, motivated person. As an added bonus, he was in great shape. However, as our relationship has progressed and we have gotten to know each other better I have found that he is quite the opposite from what I originally thought. He is unmotivated and his low self-esteem frequently causes us to argue. Additionally, he has gained fifty pounds in the past two years and refuses to get fit. 

My question is, is that are periods of feeling not attracted to one's partner/feeling slightly apathetic about the relationship a normal part of long term relationships? Like I said, he's a great guy. I just don't feel as passionately about him as I once did.
<bot>: Feeling emotionally and physically unattracted to my boyfriend. Not sure if it is a phase that is part of being in a long term relationship.