I could be off base here, but I'm sensing that you're very needy. Why? Because you went from her neglecting to say 'I love you' to assuming she was breaking up in one phone call! Holy shit, that's one hell of a leap.
If everything was as wonderful as you say, why did you even raise the topic that she'd neglected to say 'I love you'? If everything is wonderful, you should have been confident in her love and not feel the need to cause an issue about the fact she hadn't said it. Sure, it's nice to hear "I love you" from our partner. But if all is going well and we're confident of their love, we shouldn't need to hear it each time we speak.
Now, some will undoubtedly argue that she should have said "I love you" to make you happy. But is a forced love declaration really going to meet your needs? Also, she may have been cranky about you being needy and decided to not reward your behaviour.
Anyway, perhaps I have it all wrong because there is background which you haven't included. But on face value, this is how it's looking to me.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.