<human>: Our relationship was really difficult and very, very turbulent over the almost 2 years it lasted. She broke up with me in the end, but I've come to realize that it wasn't really anyone specific at fault. I was difficult and selfish at times and I let many of my personal problems affect our relationship in a negative fashion; we both suffered and were deeply unhappy.

We can't avoid seeing each other because we are in the same graduate program. Sometimes she says hi to me when she walks past, but often she doesn't. The degree of here actually acknowledging me varies depending on how she's doing I guess.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: Can't avoid running into my ex several times a week. I feel a strong need to apologize, but worry that I will just worsen things. Should I try?