Feel Like He Is Cheating

I am 24 weeks pregnant with our third child. I'm a plus size woman so I'm trying not to gain a lot of weight. For the past few days I have felt like my husband was cheating or not into me anymore. He is the only one working because I'm high risk so I can't. I am a full time student. Things between us have been really stressful lately and I don't know what to do anymore. I have checked his phone found nothing and I don't know what else too do.