In Spain, "te amo" sounds a bit too strong. Even for couples, I would prefer "te quiero". It feels more natural.

I love you... te amo. I love it.... me encanta. I love her .. la amo I love him .... lo amo. I love their .. .los amo.

I love you in Spanish is both: Te quiero/ Te amo. We can say both to the person we love, with the same meaning. The different is when we speak whith friends or relatives (not couple): we can say only "te quiero". Te quiero in Spanish is exactly "te amo" in this context, without the meaning who has in English. So "te quiero" is not "i want you". I want you = te deseo

I love you = Te amo.

te amo