I don't see it as loving someone too much but as loving in an unhealthy way.
I love my guy VERY VERY much, BUT I know when to back off, when to give him some loose and when he needs me to cuddle with.
I once was in a relationship with a guy and it turned bad bcs I was totally head over heals in love with him and had my whole future mapped out even if we had only been together for 2 months! I was really obsessed. I became jealous of every girl he spoke to and he was very immature and irresponsive to my needs as his girlfriend....I didn't love him TOO MUCH, I just loved him in an UNHEALTHY WAY!
We left each other after 3 months (thank god it didn't last any longer).