Have arguments with your GF is not all that bad thing, but if you should avoid that kind of things, use some way that she can accept to talk with her.

You still feeling good flaco? No more depression?

How is your relationship atm

Give her a rose every now and then. Tell her why you fell in love with her in the first place. Treat her like a queen. These tips may seem unrealistic yes, but it at the very least will show her that she is still a beautiful woman and can be treated like one.