When someone says 'I Love You' to someone they are in a romantic/intimate relationship with what does it actually mean?

I found it very hollow to say it to either of the two women I was with in LTR's once the true extent of the betrayals started to become clear. Esp the second partner.

So I ask - what is the true meaning behind the words 'i love you' and is the meaning genuine, or just implied with no obligation to back it up with actions, etc.?