Girlfriend isn't as affectionate anymore - she seems distant?

My partner who is 39yrs old (I'm 28) has been not as affectionate as she used to be lately.

For example, she would always text me in the mornings (usually first) when I'm at work and write lovey dovey things to me but just recently she hasn't been texting as much (if at all) unless I make the first move it seems mostly.

Oddly though in person she seems affectionate enough i. e. kissing etc.

I just feel a bit unloved, lonely and sad because I cannot figure out what is going on? She is not cheating by the way, she isn't the sort of woman to do that plus I'm a loyal guy.
Girlfriend isn't as affectionate anymore - she seems distant?
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