Sure, people get new hobbies and interests all the time, but there's usually some kind of explanation. They pick up golfing because their brother plays or they start reading Harry Potter because you finally convinced them it was incredible. But I would be wary if all of a sudden your partner decides they enjoy hiking for hours on Saturday and they don't invite you along.

You ask them if you can call the babysitter because your phone is dead, and they act like you just asked them to share toothbrushes. Major red flag. I'm not saying your partner has to be OK with you looking through their phone, but if they're not willing to let you use it to make a call or even check the time, they're hiding something in there.

Now your partner takes a shower as soon as they walk in the door from work, or they start leaving an hour earlier than usual in the mornings. Of course people are allowed to change up their day, but when there's no explanation, it sounds fishy.

There are hours during the day where your partner is totally unavailable. They always claim their phone is dead during those times, they didn't check Facebook, or they were just "busy." I don't buy it. You don't have to be in constant contact with your SO, but I call BS on someone not being able to return a simple text message or phone call for hours and hours at a time, especially if it happens often.

This one only counts if their friends were fairly open with you before, but now they refuse to look you in the eye or speak with you. It's even more of a problem if your partner claims to be with their friends, but none of them are willing to answer your calls or texts when you can't get in touch with your SO.

If I meet a new friend and start spending a lot of time with them, I'm probably going to mention it to my boyfriend. Even something simple like, "I met a friend at work today and we're going out for drinks." But your SO claims to be hanging out with a friend you've never met, and they refuse to give you any details. Who is this mystery friend? Why wouldn't your partner want you to know about them?

Things are getting sketchy when your SO is constantly irritated with you, claims you can't do anything right, and seems to pick arguments out of thin air. It could be their cheating guilt manifesting itself as anger, but I think it's more about justifying to themselves why cheating is OK. If they convince themselves, and you, that the two of you don't work together and they aren't happy with you, they can try to justify their affair.

So huge for partners who have children together, and seriously heartbreaking. You plan something fun to do with your kids, but your partner decides they'd rather go golfing with friends or out to lunch with their BFF. They have no reason to miss out on family time, but they know you'll be busy and occupied with the kids and won't be checking up on them every five minutes. Shady.

Like, a lot. They've gone from wearing a baseball hat every day to spending hours on their hair before going out with their friends. They start buying more clothes than usual, and of course, they are outfits you never see them wear.

You haven't changed your behavior, but now your partner claims you're clingy and need to give them space. Why? Because you called them when they were late for dinner? Or because you asked them to start spending more time with you? Of course you come off as clingy when they're interested in someone else and more aware of your advances.

I don't mean just once because they were too drunk to make it home. I mean it seems like every other weekend, your SO is going to a friend's house to hang out and ends up staying the night there. I mean, I love my BFF, but grown people don't have that many slumber parties.

You're in the living room, but they're in the bedroom. You're cooking in the kitchen, and they're down in the basement. When's the last time the two of you spent actual quality time together? If you can't remember, or if you realize your time spent together is in silence with the two of you doing your own thing, I'd listen even more to your gut.

Some people are pretty reserved talkers, sure, but everyone has something to share eventually. If your SO can't tell you how their day was, what happened while they were out, or even where they're going, then there's a larger problem. You don't have to drill them with questions, but if you're asking what their plans are for their weekend away and all they can tell you is, "I don't know. Just having fun," I'd be concerned.

A giant group of your friends and their partners are going out for the night, but your SO would prefer to stay home. Although some people are introverts, I think it's weird if your partner never had a problem going out before and now wants to sit home alone while you go out for the night. Who knows what they're doing or where they're really planning on going.

Hand on heart, I know that if I asked my boyfriend if something was going on with us or if he was cheating, he would be extremely upset and would do everything he could to reassure me he wasn't. That's what non-cheaters do — they try to fix your feelings and they are concerned over what they've done to make you feel that way. Cheaters, however, become incredibly defensive. They might even turn it around on you and accuse you of being the one who's unfaithful. They call your fears stupid and tell you you're just acting crazy and to get over it. In short? They're trying to knock your confidence and make you feel guilty for your fears instead of helping you become secure in the relationship again. Seriously sketchy and seriously cheating.

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