My ex girlfriend started taking phentermine and literally went from one week telling me she can't wait until we get married to i don't know how I feel about you anymore. Right after the break up she would call me at night telling me she loves me then in the morning ignore my calls and not want to hear from me. This daily I love you hate you was going on the whole time she was taking this drug and still continues to this day. Was it when she was taking it causing her to act different? I looked up side effects and I noticed it says severe mental changes. Just wondering if this has anything to do with the break up because this came as a complete shock. Literally everyday she would say I LOVE you so much, I can't wait to have kids, get married etc, to i don't know anymore. Can this drug cause something like that?