You've got nothing to lose by asking her directly. After all, as it stands now you're not seeing too much of her. My only caution would be to ask her in a way that shows you care, and miss her, and would like to see more of her (rather than in an accusatory, hey-what-the-heck-happened-where'd-you-go sort of way). And do be patient. If she's got stuff to sort out, especially ex-boyfriend stuff, it might take a while. Tell her how you feel, then step back and let her do her thing, including coming to you when she can. Good luck!..

She's back with the bf. You know it too. Admit it and move on. Bet that if she hits the skids with him, she'll be looking you up lickety split...
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Find someone in whom you can invest...
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C...

One of the problems with internet dating is that there are so many options and people are often dating dozens of people at once. It sounds to me like she texts you when she's bored or has a down time. But perhaps it's not an ex, but rather that she's been asked out by a ton of guys and she only has so much time in the week. Just tell her to let you know when she's free if she wants to get together again. (Maybe she really is 'busy' but people tend to make time for people they want to be with.)..