Huh, I realized I actually say "I love you" and "I love you too" to my mom when I hang up the phone but not to my husband! He *hates* phones though and is likely to just disconnect abruptly when he''s done talking though... at first when we were dating I thought he was being rude or was angry or something; now I''m quite used to it and it''s just one of his quirks. My mom hates it when I say "me too" if I''m talking on the phone to her at work in front of customers- she always assumes I''m upset or something- so I never do that anymore!
In person my husband and I say it a few times a day I think, always "I love you" and "I love you too"... and sometimes we do "I hate you/I hate you more" said in super sappy tones if we''re feeling silly.