Can you be attracted to someone and they become unattractive over time?

I've been with my boyfriend for 6 months. He travels for work so we've spent about 3 months together. We've only been intimate 3 times all the other times he was in town I've been on my cycle. Or he just doesn't want sex only oral. I've asked him about it numerous times he will change the subject or says he's too tired. I've asked him does he like having sex with me he just says I'm being crazy. The last time we did have sex he only did it because I nagged him. Could it be he's not attracted to me?
Can you be attracted to someone and they become unattractive over time?
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