惰性に身を任せているがために今のような現在があるんですね。

tbd

I've ended up in my present state from having indulged myself.

高校時代からつきあっている彼氏はいるものの、つきあいが惰性になっていると感じ、不満をつのらせている。

tbd

She has a boyfriend she's been going out with since high school but feels their relationship has become a matter of habit and is increasingly dissatisfied.

She has a boyfriend she's been going out with since high school, but she feels their relationship is in a rut, so she's become discontented.

She has a boyfriend she's been going out with since high school, but she feels their relationship has stagnated, so she's become dissatisfied.