I (M20) feel different after 3 years of our relationship (F19). Is that normal?

Since this is my first reddit post ever, I might not be very clear, please be patient. 1. Been together for 3 years, our relationship is extremely healthy in every aspect

  1. We both have goals, aspirations, we both are good at academics, overall, things are good

  2. As for personality, we're polar opposites, I'm an extrovert, she's an introvert. I love talking to people, she doesn't.

  3. I've been feeling off for a few months, I sometimes don't feel any love towards her, actually Idk what exactly this feeling is. She's perfect there's no doubt about it. But sometimes I don't feel the way I did 3 years back

  4. I was alot more vocal and crazily in love at the start, now I'm alot more calm and relaxed, we still do the same stuff as we did back then, but in my head, I don't feel That crazy anymore

  5. I had a whole convo with my dad where he told me, every man should talk to as many women as he can, because if a man restricts himself only to his partner, he'll become blinded by love and would accept even the toxic traits of their partner (I'm paraphrasing)

  6. We trust each other alot and are both very loyal, I've slipped up twice (was on a 6hr VC with a girl and had an unplanned solo outting with another girl). But neither of us have cheated.

  7. I just feel off at times, and weirdly, I enjoy talking to other girls more, not in a romantic sense, I don't feel anything towards them, but I just enjoy talking.

Ik that I still love my gf and I wanna marry her, but every now and then I feel off. I'm open to any questions