I think it depends on where you are in your relationship. I honestly had two fights ever with my husband before we had children (about 4.5 years into our relationship). We really didn't argue and we had a pretty relaxed, laid back approach to everything. Post-children, yes, we argue. We still have only ever had maybe 6 serious arguments ever where I genuinely thought, can I actually live with feeling like this or could something like this end our relationship? They weren't about cheating or anything horrible like that, just fights about a stressful situation in the extended family and about needing more support around the house to balance work and parenting. We've been together nearly a decade, so 6 fights doesn't seem like much to me.
But yes, I think it's weird not to argue at all or have any disagreements, but it very much depends on where you are in your relationship. If you are just dating and it's still earlier days, no kids, don't live together, share finances, have older parents you're caring for, etc., life is probably pretty simple and I would see it as a good sign that you aren't arguing about petty things. If you've been together 10 years and have never had an argument, despite kids, moves, job changes, serious illness, etc., then I would see it more as a sign that one of you just avoids serious conversations or disagreements that could turn into arguments, which is probably not a good sign for your relationship. My mum and stepdad almost never argue, which is fine for them, but it's mostly because she just agrees with everything he says as she hates conflict, which I don't really see as a positive, though it works for them.