Should I break up with my 3 year relationship girlfriend

I'm working abroad and I'm only home for a 3 day weekend every 3 weeks, she lovely to be around when I'm there and with her but only recently I've gone abroad I gave her the option that if she wanted to end it I wouldn't blame or hate her, but we call every night while I'm away and she seems to have no interest in my new job or anything that I'm doing she seems annoyed at me but that's what I expected but it's worse than expected, when I come home it's like being with a completely different girl, but when away she doesn't even text me it feels like I'm desperate all the time. I just wanted to know people opinion should I break up with her to make her happier because she's constantly upset bipolar kinda way she's up and down would it be better for her and even me because I constantly worry about her and love her, but if it would make her happier I'd do it in a heart beat she's had a hard life and I just want her to be happier.