[I definitely have the instinct that I tend to avoid the phrase 'I love you' in writing.]

Having characters actually directly say what they're thinking or feeling is almost never the interesting path, though! Unless they're making a deliberate effort not to say what they're thinking or feeling.

I can't remember where I ran into it, but there was this internet snippet going around about one of the best writing exercises someone had run into being "Write two characters having a heated conversation, except that under no circumstances can either one come out and say exactly what they mean." Keeps things lively.